Pneumatic Routers for Shopbot

[kaaboom_99]

I haven't read any postings on someone trying a pnuematic router in their SB. These routers turn anywhere from 40,000 to 75,000 rpm @ 90 psi while using very little air (in the neighbourhood of 2-7 cubic inches). Has anyone tried this method of tool use yet? Just curious whether the purchase of one of these air routers is justified or not.

[sheldon@dingwallguitars.com]

I'm using a small air turbine running at 65,000 rpm, piggy backed on my Acc. axis. For running small diameter bits 2.0 mm and under it's the only way to go. They have a very narrow torque band though so if pushed too hard will stall.

[kaaboom_99]

I had thought about using this type of router for some printed circuit board engraving. I will probably be using endmills with a 1/8" shaft and a 0.005 to 0.015" cutter. I have played with my cad software for designing the boards and have successfully imported and got the SB software to cut out the file (atleast in preview mode. Still waiting for my machine to arrive.)
This was the reason for the post. Thanks for replying Sheldon.

[sheldon@dingwallguitars.com]

This link was given to me by Ed Coleman. I found it very useful.

http://www.thinktink.com/

[donframbach]

Hello Sheldon, what type of air turbine are you running?
TIA Don Frambach

BTW the http://www.thinktink.com link is great!

[sheldon@dingwallguitars.com]

Air Turbine Tools #201JS.

They have a lot of models to choose from, I suggest giving them a call to discuss your application.

www.airturbinetools.com
800/840-4019

[donframbach]

Hello Sheldon,

I just received a catalog and CD from Air Turbine Tools and am getting really excited about replacing my Bosch router with an air driven tool. May I ask two questions?

1) I would run 1/16, 1/32, and smaller bits. Do you know how much noise these would make cutting at higher speeds?

2) I don't have a compressor. I would use it only for this purpose. Can you suggest what I should look at?

TIA Don Frambach

[Wdyasq@yahoo.com]

Hello Don,

Buy more compressor than you think you need. If you ever start using quality air tools, sanders, drills, screwdrivers and other such stuff, I think you will like them a lot better than the electric counterparts. Spray guns running on compressed air can produce nice finishes and air will be used for 'blowing off' your tables and such. Also, the venturi type vacuum devices can be used for hold-down devices.

When you consider air tools remember to properly plan your air lines. They should not be PVC. They will need to have 'drops' and drains for both the tank and the lines. Will the tool need a regulator or lubricator? Will you need a line dryer?

I don't want to sound like a spoil sport but, a good 5 hp compressor SYSTEM can set one back $2000 or more in parts alone by the time fittings, pipe, motor starters, dryer, regulators, couplings and air lines are figured in.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[sheldon@dingwallguitars.com]

Good points from Ron. My compressor is a 4hp Quincy (I don't recommend Quincy) single stage w/80 gal tank, which puts out about 14 cfm at 90 psi. It seems to be running about 30% of the time when driving the turbine. This seems kind of inefficient to me since it's taking 4hp to get .25hp at the bit. However, the system works well so I'm not in a hurry to fix it


The tool needs very clean air, so a 5 micron filter/regulator at the tool is needed. Also an after-cooler and water trap should be used at the compressor. You can make a surprisingly good after-cooler using a 25' coiled hose spread out with an acrylic loom and submerged in a 5 gallon bucket of water. Hot air goes in, cool air comes out, then on to the water trap. Copper tubing would be better, but this works OK.

I haven't cut a lot of wood with mine yet. Mostly brass shim stock and fibreglass PC board, which are both pretty loud. Loud enough for ear plugs, but still about a quarter of the volume of a router.

[Wdyasq@yahoo.com]

I've had a 5 HP Quincy for years. I have changed the oil. I have run the compressor and run, and run.........

One of the best 'cheap' after-coolers is an automotive refrigerant condenser. You can rig a fan up to the motor windings and with the AC condenser between the compressor head and the tank drop most of the heat and water right there.

Air is not an efficient tool operating medium. Of course any time energy is converted from one for to another, power is lost. Still, my favorite 'trim' router is an old Rockwell air-router. My favorite sanders are air as are my favorite drills.

The biggest improvement one can make on an air system, IMO, is a refrigerated air dryer. It also lowers maintenance on you air tools- and air tools are almost non-maintenance.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[David Fisk]

Sheldon,
I was wondering how much your air spindle cost? Have you had any trouble with bit breakage with the small diameter tools? I've been trying to figure out the best spindle for our cutting of puzzles and I have been considering air. I've used Think & Tinker bits with my laminate trimmer and I keep breaking them. I don't get very far and they break regaurdless how slow I'm going. I've been trying to figure out what the trouble is. Vibration in my machine or what. What type of shopbot are you using ie. do you have the latest with steel table. Mine is wood and I'm wondering if that could be a vibration problem.

[David Fisk]

I looked at www.airturbinetools.com and found they have units with as much torque as 1.5 hp. The air requirement is quite high though

Air Consumption-Idle cfm (L/s) 14(6.60) 14(6.60) 23(10.84)
Air Consumption-Stall Flow cfm (L/s) 60(28.30)
Does any one know what the L/s means in this ratting?

[gerald_d]

Hi David, the L/s is the litres per second. (Just an alternative metric unit)

BTW, the 1.5 hp is not a measure of "torque", but rather a measure of "power".

"Torque" would be measured in "inch.pounds" or something similar.

Be careful to try and compare the "horsepower" of air versus electric spindles. These two industries use completely different ways of measuring the advertised "HP". The air guys tend to be conservative, while the electric guys are always optimistic.

[donframbach]

Hello David,

I have not (yet) broken a 1/32" bit that I have mounted in my Bosche 1617EVS router. I just received some even smaller bits from Think & Tinker so I don't have experience with those. I got the 1/32" bits form Flamingoveneer.

http://www.flamingovener.com

Don

[donframbach]

David,

Try this link for Air Turbine Tool prices:

Its kind of long so you may have to "copy and paste"

http://www.jlkdirect.com/Search/result.asp?PN=adv_search3&C=&PG=PTO%23POWER+TOOLS+ %28AIR+%26+ELECTRIC%29&MFR=AIR+TURBINE+TOOLS&entry =201JS&submit1=Search (http://www.jlkdirect.com/Search/result.asp?PN=adv_search3&C=&PG=PTO%23POWER%2BTOOL S%2B%28AIR%2B%26%2BELECTRIC%29&MFR=AIR%2BTURBINE%2 BTOOLS&entry=201JS&submit1=Search)

Don

[sheldon@dingwallguitars.com]

Ron - I have no problem with my Quincy compressor head, it works fine. The tank though was quite light weight and developed cracks by the welds after less than 4 years of use.

David - I paid roughly $700 CDN or $500 US for my spindle. I've been running mostly larger 2mm bits in it with no bits broken so far. I would check the runout on the laminate trimmer. The folks at Think and Tinker suggest 20,000 inches before their 1/32" cutters need replacing.

[David Fisk]

Sheldon,
How are you mounting your air spindle?

[David Fisk]

I just checked with Air Turbine tools and they recommended model 230A for cutting wood. This is available in 30,000 rpm and 40,000 rpm.
It requires an enourmous amount of air though. between 7cfm to 34. To get a compressor capable of that high number it would require either 3 phase 10 hp or a duplex 5hp design. Either way those are big bucks. I was hoping that a $1600 7.5 hp compressor with 24 cfm would do the trick. :-(
If you had 24 cfm @ 175psi should the cfm go up if you regulate the preasure to 90psi? 90psi is what the spindles supose to run at.

[sheldon@dingwallguitars.com]

David, my spindle has a 3/4" mounting arbor on the top of it, so it was a simple matter of mounting a split block with a couple of pinch bolts.

I find it odd that they would recommend such a large spindle. The 230 A is over 3/4" HP and will take a 1/4" shank. That's way overkill for bits 1/32" and under. For 1/8" bits and up, an electric router is much more cost effective. What sizes of bits are you planning on running?

If you need to run large bits sometimes and miniature other times, you could get away with a smaller air spindle and piggy-back it next to a router.

[jim_melton]

Forgive me if I'm speaking out of turn, but I keep seeing all of this traffic on Air powered tools for use on the SB.

I don't really understand WHY anyone would want to spend that kind of money to do that.

What are you guys cutting that requires bits that small? Or is it a noise factor thing?

Would it not be more cost effective and energy efficient to just use a ROUTER like the Porter Cable and use an ER-16 MINI Collet setup to get down to bits that small?

The ER-16 can be purchased with a 1/2" Dia. Straight Shank that will chuck up into the router. You might lose an inch or two of Z travel, but a good machinest could shorten the shank for you.

And you can purchase the whole setup (Several of them for that matter) with collets to go from 1/32" to 3/8" shank for a WHOLE lot less than what it would cost to buy an Air Compressor that would supply that kind of volume, and all of the required dryers/oilers.

Jim Melton
864-862-9212

[gerald_d]

Jim, I think the main part of the answer is the extreme speed needed for the tiny bits. If you halve the tool diameter, you want to double the rotation speed (rpm) to maintain the same tip cutting speed (inches/second).

20 000 rpm for a 1/2" bit is theoretically equivalent to 320 000 rpm for a 1/32" bit!!!!

[donframbach]

Jim, your points are very well taken. I am currently using a Bosch 1617 router with a 1/4" collet and a 1/8" collet adapter to cut detailed small signs with a 1/32" bit (1/8" shank). I have recently purchased smaller bits (1/8" shank) from Think and Tinker. I have a problem in that I must run my system as quietly as possible. Consequently, my router runs at slightly less than full speed and my feed rate is only 0.2 in/sec. This means that it takes about an hour to cut a small sign and much longer to cut larger ones.

I have also found that the long run times are taking a toll on my router.

I was hoping that a small air driven router would be quieter, more durable, and say running at 40K rpm would allow me to increase the feed speeds.

I would appreciate any comments before I commit to this.

TIA

Don Frambach

[sheldon@dingwallguitars.com]

Jim, the runnout on laminate trimmers and "affordable" routers is too much for such small diameter cutters IMO and as Gerald mentioned the tip velocity would be very slow.

My intended purpose was to run .025" bits to cut fret slots and inlays in guitar necks. I have yet to do anything more than test cuts in that area, but I've found uses for the tool to cut brass shim stock and PC board profiles and traces.

Don, I don't mean to sound like a speed freak, but the feed rates for a 1/32" cutter (depending on the style of cutter) at 40,000 are only about .4-.5 "/sec. 65,000 will still only get you closer to .6-.8"/sec.

[David Fisk]

Sheldon, I've been trying to use Think & Tinkers 1/32" bits with my laminate trimmer. I'm trying to cut 1/4" thick baltic birch. I tried some of 1/32" bits with a .26 inch long cutting edge. When I spoke with the Air Turbine folks I said I would also like to cut with 1/8" bits. I thought that they would need to go as fast. I'm pleased to find out they don't need to. I also told them that I wanted to cut in one pass.
I've had problems trying to do multiple passes . . . but that is another forum thread (probably b/c of my tables rattle). I'm considering abandoning the 1/32" bits and just using 1/8" bits and cutting around the puzzle pieces and then imprinting the assembled puzzles. This would give me a potential zero kerf puzzle.
Thanks for all your input.

[donframbach]

About to buy an air turbine spindle. Would greatly appreciate any comments.

From J&L Industrial Supply:
. Air Turbine Tools 201 JS 40,000 rpm spindle
. (requires 1 CFM air at idle and 8 CFM stall)
. $401.00
. Air Turbine Tools 5 micron filter/regulator
. part number #30003
. $81.50

From Amazon:
. Thomas 2HP 4gallon (13 amp 110 volt) compressor
. (I only have 15 amp 110 volt service)
. 4.6 CFM @ 100 PSI
. $369.99

[sheldon@dingwallguitars.com]

I think you are undersizing your compressor. The tool will likely be running closer to the 8 cfm.

My understanding is that you need to be aware of the duty cycle of the compressor. Most are I believe 50%. In other words you would need one that puts out 16 cfm @ 90 psi to make full use of your tool and not be overworking your compressor.

Also, don't forget a good moisture trap.

[donframbach]

Sheldon, I appreciate your comments.

I must confess that I was extrapolating from your compressor specs. I understand that using 2mm bits with a 65,000 rpm spindle and a compressor output of 14 cfm, your duty cycle was about 30%. I was planning to take light cuts (about .05" with .0313" (and smaller) bits) with feeds of .2-.5"/sec. I assumed that with a 40,000 rpm spindle my air consumption would be a lot less than yours. (Air Turbine tools says 40k 201JS model consumes 1 cfm at idle while 65k 201JS consumes 3 cfm at idle.) I assumed, perhaps incorrectly, that air consumption with these light cuts would be near idle.

I would greatly appreciate your thoughts. It would be a major hassle to get 220 service to my shopbot. That is why I am thinking about only a 2HP (13 amp 110 volt) compressor.

Don

[gerald_d]

An aside:

If a 110 volt (13 amp) outlet can only drive a 2HP compressor motor, why do the router suppliers claim that they are giving you 3.25HP. . . . .?

A router of the same physical size as the American 3.25HP would be called a 2.4HP (1800watt) in other countries. This is the maximum power output from a 120V 15amp outlet: 120 X 15 = 1800Watt = (Multiplied by a factor of 1.34 = 2.4HP).

The maximum power available from a 13 amp 110 volt outlet = 13 X 110 X 1.34 = 1.9HP. Therefore, those of you who have your 3.25HP (Nominal)routers plugged into 110V 13A outlets, are getting no more than 1.9HP in the language of the air spindle guys, and in the language of Donald's compressor guy.

[Wdyasq@yahoo.com]

Donald,

I'll agree in thinking you are a little 'light' in the compressor department. I doubt your air consumption will change much with bit load. When compressors are "worked hard" they "make water".

Gerald, I'll have you know I can run my 3.25 HP router AND my 2 HP shop Vacuum on the same 20 amp circuit. I'm thinking about hooking a generator to one of these motors and selling electricity back to the power company. America is a progressive country and NOT ruled by those old laws like physics or gravity!

Or truth in advertising either.


Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[sheldon@dingwallguitars]

Gerald, I think the 3.25 HP spec is the point at which your armature windings start to glow



Don, I don't feel I have enough experience or knowledge of your project to offer much other than a few observations: Think and Tinker suggest that their bits are designed to take full depth passes. So don't be afraid of taking a .250" deep pass if you need to (just don't do it with your last bit)
Two passes at .2"/sec is slower than one at .4" if there are any Z moves involved.

One far out question - how far is it to the nearest outlet that could handle a larger compressor? Could you run an airline instead?

[gerald_d]

Hahaha . . . Actually, the reason behind it is the sine wave nature of the alternating current supply. The router guys measure to the peak of the wave, while the other guys take a sort of "average" value called RMS (Root Mean Squared). The difference between PEAK and RMS is 1.414 times (square root of 2).

[donframbach]

May I ask a naive question about compressors? I assumed that I wanted to get an oil-less compressor to protect the Air Turbine Tool and to keep my work area free of oil. I spoke to a friend yesterday who didn't think that oiled or oil-less made any difference to the tool or to work area cleanliness. He thought that an oiled compressor would be more durable. Where does the oil go in an oiled compressor?

[Wdyasq@yahoo.com]

Donald,

The real problem with air tools is moisture. Not much oil gets past the rings of an oiled compressor. That that does collects and, due to the wonderful laws of gravity, settles to the bottom of tanks or lines. So little gets to the tool that if you want an air tool 'oiled", you add a device to oil the tools.

HTH,
Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[donframbach]

Ron, does that mean that the ONLY reason for having oil-less compressors is that you don't have to fool around with oil (and with leveling the compressor for the oil system)?

Don

[Wdyasq@yahoo.com]

Don,

Saying something is the ONLY reason would be like thinking a Politician is ONLY interested in your well-being. There can be many reasons to use an oiled or 'oil-less' compressor. I don't think you are going to use the air for a 'fresh air' source and actually breathe it but, you don't want to use an oil lubricated compressor for that.

Call me old-fashioned but, I like oil lubricated compressors. My father's shop had two. They were well used when I became aware of them at about the age of 8 or so. They were still working when the company was auctioned thirty years later. My present compressor is about 20 years old and gets a few ounces of oil added between oil changes, once a year. I don't know of any 'oil-less' compressors giving that kind of service with any substantial volume of air.

I have many air tools. I use the sanders, drills, grinders and air shears more than I use their 'equivalent' electrical counterparts UNLESS I am in too much of a hurry or it is such a small job I won't wait for the air-pressure to build if the compressor is not 'on'. I have one air router, an old Rockwell, that is becoming my favorite trim router.

BTW, I have my compressor about 100' from the shop and use a radio relay to switch it on/off. I recommend having your air-compressor far enough away to eliminate any noise problem and switching it on with some sort of remote switch. Don't forget to drain the water in the tank on a regular basis.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[gerald_d]

Even breathing air can come from oil-lubricated compressors, such as for filling SCUBA bottles,
but some spray-painters don't want any trace of oil. . . . . .

The actual rate of oil consumption in good industrial compressors is close to zero. Our 30 year-old has probably had 2 oil changes in its life with no topping up in-between. The oil compressor would be less hassle than an oilless, IMHO.

[David Fisk]

I would think that the oiled compressors would run cooler and thus you would have cooler compressed air with less water in it.

[david_fisk]

Sheldon, I was wondering how you mounted your 201JS Spindle. They have a 3/4 shank comming out of the back and I was contemplating replacing it with a 1/2 bolt with the head cut off and chucked into my 3&1/4 HP porter cable router. That way removing the air spindle would be as easy as replacing a bit. Do you think using a bolt like this would be good enough? The other option would be to have the shank that comes with it turned down to 1/2. I'm trying not to do that if I can help it at least until the spindle has proven itself for our needs. Air Turbine tools has a 10 day trial period which I think, in my case, wise to use.

Of course I could get the 201M which is designed to be mounted around its body like the shopbots mounting system. It's a little bit cheaper to go this route but then I'd have to come up with a way to mount around its barrel.

[sheldon@dingwallguitars.com]

5178 I used a scrap block of aluminum, drilled 3/4" then split, added pinch and mounting bolts and bolted it to the side of the standard motor mount. I had to move the motor mount to make room. As you can see, it's a tight fit.


5179 The collet heights are set so that one doesn't interfere with the other provided the collet and bit are removed.

Talk to Air Turbine about replacing the stud. The stud should be hardened, needs matching threads and a shoulder to tighten against the tool or it will wobble.

You would also need to come up with a system to keep the the tool from rotating.

[donframbach]

Well, I did it! I just installed the Air Turbine Tools JS 201 router (rated at 45K). I also bought the small 110 volt 2HP compressor. It works (sort of). The router cuts very well. There must be much less runout than with my Bosch router. The compressor is another matter. I figured the duty cycle would be about 30% when the router was at idle. Compressor is rated at 4.6 cfpm at 100 lbs/in2 and the router specs say 1 cfpm at 90 lbs/in2. Actually the compressor duty cycle is about 75% at idle and about 75% when using a 1/32" bit at .05" cut depth. I ran the compressor like this for about an hour and was able to completely cut a small sign but I wonder if larger jobs will make it overheat. It does have "thermal overload protection" so I plan to give it a test soon with a bit up in the air so that I don't break anything.

You guys were right. A bigger compressor would have been better.

Don

[sheldon@dingwallguitars.com]

Don,

My compressor gets pretty hot when we're running air tools. A temporary band-aid solution is to run a fan across the head.

Incidentally, my circuit board routing is working out great. I broke my Think and Tinker bits before I had a chance to dial in the speed, but I've been having good luck with some surplus bits I had on hand.

[Wdyasq@yahoo.com]

Don,

It may be worth your while to turn the router off/on with one of the output switches. An air motor doesn't care much about start/stop cycles and it will save some air. With a marginal air compressor I would also consider a "Low air pressure emergency shut-off" where if the air pressure got below the safe operation pressure it would stop the ShopBot from cutting.

Thermal overloads usually trip due to low voltage. Low voltage is commonly encountered from too long or too small extension cords.

The real problem I see with hot air is the ability to carry moisture. This moisture will wash the lubrication from the tool and cause short life. Turbines should not be highly susceptible to this treatment.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[sheldon@dingwallguitars.com]

I just finished engraving our logo in an aluminum mould master using a .025" endmill flooded in A9 and the air turbine. I can't believe how well the system worked.

Now, will vacuum formed ABS pickup the detail...?

[david_fisk]

I just finished testing the JS 105 65,000 rpm turbine. Wow,supper smooth cuts. Eliminated my bits breaking, I was having troubles with my Y axis loosing a step here and there. I swaped my y and z drivers and the problem seemed to go away, but then aparently it happened to my z axis. It ended up plunging too deep and well now I'm planing on soldering in a new driver chip. It's funny I could cut some puzzles with little or no problems but others were consistantly off. I checked the sbp parts file in Ed Colemans preview program and could not see these problems.
So my question is is it possible for one parts file to stress out the driver boards more then another?

[donframbach]

Sheldon and David,

Do you find that your compressor tank collects water when you use the air turbine tool? (I assume that you are using the 5 micron filter and regulator specified by Air Turbine Tools.)

The reason why I'm asking this is that I have not collected a single drop of water in my compressor tanks when using the Air Turbine Tool. My compressors instructions are very explicit about removing water from the tanks (every 4 hrs). (It's a pain to "drain" the tanks.)

My setup is as follows:

Two Thomas 2HP twin tank compressors linked in parallel so that they each have a duty cycle of less than 50%.

A cooling coil consisting of 10 feet of copper pipe.

About 10 more feet of compressor line that connects to the 5 micron filter (which does collect a significant amout of water)

About 10 more feet of compressor line that connects to the Air Turbine Tool.

I wonder if the water is condenses only when the pressure drops to 90 PSI. It remains 135-110 PSI in the line proximal to that.

TIA for you help.

Don

[rgbrown@itexas.net]

Don,

There are a lot of little things one can do to an air system to make it supply clean, dry air. The reason your tanks don't collect moisture is they heat up. Air will not hold as much moisture at pressure than at atmospheric pressure. Hot air can hold more moisture than cold air.

The best place for an air cooler is the outlet of the air-compressor and before it gets to the tank. An old car air-conditioner condenser coil works well. A fan can be added for more cooling.

From the tank, the air lines need to facilities for draining collected water. Many shops use Iron pipe overhead with 'slope' to the pipe and 'drops' for the air connections. These 'drops' usually have a slump to collect the moisture.

The systems supplying really dry air have refrigerated air dryers and automatic sump drains.

PVC pipe should not be used in an air system. The shrapnel a PVC pipe under pressure makes when ruptured makes an interesting 'Shop Grenade".

I am going to have to 'redeaux' my shop air lines this year. I am planning to use KITEC pipe: http://www.ipexinc.com/kitec/

This pipe is a flexible plastic lined and coated aluminum tube and can take turns and bends easily. It does require special installation tools that can be rented locally.

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[david_fisk]

Don,

My air comes out of the compressor into a regulator where I lower the preasure to about 120lbs then through a 50' copper coil submerged in water. From there it goes to a cheap water trap then to the 5 micron filter then to a coelesing oil filter, through another regulator to 90 lbs, then through 20 feet more of air hose to the tool. I get water in both the tank and the first cheap water trap. In the 5 micron filter I get very little condensed moisture, so little I don't need to empty it. I was thinking of adding some desicant material to the 5mil filter to get any remaining moisture. My compressor gets very hot, but maybe the Florida humidity causes all this extra tank moisture.

[waynelocke]

I have been told by a pnematic dealer that schedule 80 plastic pipe meets code for air lines. I am planning on using it because it has the same ease of installation as schedule 40 — I think.
Wayne Locke

[sheldon@dingwallguitars.com]

There's not much I can add. Kitex pipe sounds very cool. I would stay away from iron pipe due to rust, and I would stay away from plastic pipe due to complications it creates if there were to be a fire (pipe melts and ruptures, escaping air aids combustion).

Heavy wall copper seems to be one of the better solutions.

[edcoleman]

One thing I've heard about plastic pipe is that it has schedule 40 strength at normal room temperature, but if it is in a cold area (i.e. an unheated shop in the winter) the burst strength goes way down and you can get the "shrapnel" effect mentioned above.

I don't know this for a fact, but it is what I have been told.

[rgbrown@itexas.net]

"I don't know this for a fact, but it is what I have been told."

I KNOW IT AS AN EVENT......and, as I remember, it was schedule 80, and not the puny schedule 40. If memory serves me it was quite cold that day and the airline took a small 'shock' that was an abnormal occurrence.

I've done quite a bit of research on airlines and, for my purposes, I believe the KITEC stuff is right for me.

As they say on the window sticker - "Your mileage may vary."

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[gerald_d]

I positively go along with Sheldon - go for plain copper pipe, as used by plumbers for normal domestic use. All our local hardware stores have it, and the correct brass fittings and accesories. Very economical and the pipes that my grandfather put in 50 years ago are still in daily use. (Not familiar with your wall thicknesses and low temperature conditions)

I fail to see the advantage of a plastic lined aluminium pipe over copper. In fact I get a little worried when plastic is used to protect metal. . . . . . . . .

[donframbach]

I'm having an interesting problem with my compressor(s) (actually I have to use two to properly drive my air turbine tool). When the compressors start up, evidently they cause a surge that can affect the positioning accuracy of the shopbot. Since I have two compressors, each drawing 13 amps (110 volts), I have plugged them into different circuits 20 amp circuits. I tried to share one of these circuits with the ShopBot and found that the ShopBot would accumulate small errors in "X" axis positioning. I am now running one of the compressors via an extension cord plugged into a separate circuit in tbe house. (I am using 14 guage 25' extension cords as specified by the compressor manufacturer). This circuit also supplies my office computer. I have discovered that the UPS to my office computer triggers every time the compressor starts but the computer seems to function just fine. I wonder if a UPS would solve my problem with the ShopBot. If so, how big should the UPS be?

Thanks in advance for your comments.

Don Frambach

[joecrumley]

Don,

Perhaps you have allready solved the problem which is a weak link in your electrical system. A pull down in current sounds like borderline supply.

I am wondering why you have gone to turbine motors? The turbine units I have, makes a lot of noise, without much power. Can you recommend a turbine? They have admirable qualities.

We have a double stage 14Hp compressor(220V) which makes plenty of noise. My experience with compressors has been to large it better.

Joe

[David Fisk]

Joe,

I've been using the Air Turbine Tools #201JS. I purchased the 65,000 rpm model. In most cases I get a cut that is sanded smooth. With a feed rate of 1.5 inches/sec. My compressor has 24 cfm's at 7.5 Hp.
Note: I'm only cutting through 1/4 baltic birch and in two passes. My tool diameter is 3/64"

[donframbach]

Hello,

I just mounted a $50 Dremel tool on my Shop Bot. Although it only goes to 30K rpm, it has much more power than the Air Turbine Tool router, it is much quieter and simplier to operate than the compressors I've been using. I sure wish I tried this before.

Don

[David Fisk]

Don,

I tried that but was breaking bits left and right.
I don't break them with my air turbine its much more concentric then Dremels. However I found out the real problem with breaking bits had more to do with my machine. I had a slipping pinnion gear, which ShopBot helped trouble shoot and also fixed for me. It was my Y axis. It would happen randomly so it was hard to find. I invested in a gigantic 7.5 hp compressor so it dosn't cycle too much. I do like the 65,000 rpms on the airturbine. It gives a very smooth surface that dosn't need sanding. So I guess for that reason I like the air turbine. I'm glad you got something that will work for you. Too bad for all the money going out the window.

[donframbach]

David

I have not broken a bit yet.

Don

[David Fisk]

That is reasuring. Do you use bits smaller then
3/64"? I can cut really well with this diameter, but if I try the 1/32 sizes I still end up breaking them, even after my shopbot being fixed.
I've been toying with the idea of making my own z carriage that is extended across the y carriage to allow multiple cutters for dupicating. I like the idea of the dremel for cost savings. I wonder though if it might generate too much vibration with multiple tools running. The air turbines don't seem to have much vibration at all.

[Brent Moore]

My Quincy air compressor dealer fixed me up. With
a proportion valve. I use it with my venturi vacuum.
When I turn on the valve. It lets my air compressor run
continues. When the compressor reaches the tank limit. It
releases the presser into the room. When the tank is under
The limit. The valve switches. To pump presser into the tank.
Starting and stopping will kill an air compressor. If
You are consuming large amounts of air.
Continues run will extend the life of your compressor.

[David_fisk]

Brent, how much did you pay for the proportion valve. Sounds like a great weigh to save the compresor and the electric motor etc. Current draws on startup are huge.

[donframbach]

David, I have used only a 1/32" bit so far for actual work. I played a little with a 1/8" bit which worked fine. I have .020" and .015" bits but have not needed them so far. Using the 1/32" bit, I cut white oak and red oak .08" deep at .2"/second running the bits at 30k rpm.

Don

[edwardmc]

A new shopboter here I just cut a black walnut plack for some red oak letters I cut yesterday and had good luck using a .0635 up cut sprial bit I just used my 3 hp porter cable and a zip bit adapter from 1/4 to 1/8 at 0.5667 feed and plunged 0.2500 18,000 rpm. Do you think I can do the same with smaller bits I have them down to .008 or do you think I should go to a drimel or air turbin . I was thinking I could just make smaller plunges with the smaller bits I would love some feed back from some one that has tryed to cut with small bits

[donframbach]

Edward, the Air Turbine Tool Router works very well with small bits. I have successfully used bits as small as 0.020" (never tried a .008" bit but would expect it to work as well) Problem with the Air Tubine Tool Router (at least for me) is that it needs lots of air. I used two 13amp compressors to keep it happy. Even with these two guys running, they got so hot that I had to program in cool down periods into my part files. This led to a need to construct an external timer, deal with the interrupt nature of the ShopBot input switches, and set up a pneumatic switch to turn the router on and off. Furthermore, the Air Turbine Tool router worked fine for bits 1/16" and smaller. It stalled when I tried to use 1/8" bits even when removing very small amounts of material. Finally, the Air Turbine Tool router was expensive to buy ($450) and very expensive to run (two compressors).

In contrast, the inexpensive Dremel tool ($50) seems to work as well as the Air Turbine Tool Router (at least with 1/32" bits). It also has the power to easily cut with 1/8" bits. (and is much quieer than a full sized router.)

I used a Bosch 1617 EVS (2HP) router to cut with 1/32" bits. This worked fine until the router failed because of the multiple long cut times ($200 to replace) The Dremel tool itself costs only $50 and replacement brushes cost only $4 a set so the expected failures (none yet) will be cheap to deal with. For me, at least, the Dremel tool seems to be the way to go.

Don

[David Fisk]

Don, My compressor was geating really hot, so i pointed a fan at it and opened the door and it now runs fairly cool. During a 7 minute cut my compressor would turn on for about 3 minutes.
I probably was pushing my 1/32" bits too fast. I had the ShopBot cranked up to 1.0"/sec. With the 3/64" bit I am able to go as fast as 1.5"/sec. Without breaking any bits. I cut in two passes. The first one I take out about 60% of the material at 1.5"/second. The second pass I have to slow down to 1.0"/second to help prevent my parts from comming loose. I'm cutting 1/4" baltic birch plywood. I can cut all the way through but I have to slow way down and this causes the bit to get burn marks on it and shortens its life. I've found the fast speeds keep the bit in fairly good shape. I also clean the bit between cuts with a green synthetic scrub pad.

[sheldon@dingwallguitars.com]

I think the key here is what size of bit you intend on running. The smaller the bit, the more accurate the spindle has to run. I don't think there is any way a Dremel could handle bits below .030". I've broken 1/32" bits in my Dremel routing manually and I was being pretty careful.

It would be nice to find a source for a high-speed (50,000 + rpm) electric spindle if there is such a thing.

[David Fisk]

Sheldon, There are such things. Columbo Spindle makes some that can go (with ceramic bearings)up to 100,000 rpms. They are special order items, and quite expensive. They require a high speed controller and I believe they are liquid or air-compressor cooled which requires a cooling pump/compressor, water/air lines ect. They cost a lot more than a big air compressor and a air turbine. Here is a link if your interested http://www.pdscolombo.com/manual.html

[pappy]

Sheldon,
Snap-on sells (called Blue Point) an air-powered pencil type die grinder that exceeds 50k rpm. It is about the size of the Dremel flexi shaft.

[edwardmc]

Donald
I was wondering if you could send a pic of how you adapted your drimal to the the shopbot . I have one and would like to give it a shot. I have a die grinder allso but I'm not shure of the rpm . I well look at it tomarow.

[donframbach]

Edward, I sent you an email with a photograph attached to it. I couldn't figure out how to post a photo here.

The mounting system can be described as follows:

I kept the same mounting system for routers provided by ShopBot. This is important to me because I want to be able to easily switch back to my Bosch 1617 router. The Bosch Router is 3.5" in diameter so I made a 3.5" diameter column of plywood disks glued together (also secured with a bolt running down the center). I purchased a Dremel tool holder and base for about $25 (Dremel #2217). I disassembled the tool holder and discarded all except for the portion that grasps the Dremel tool. I then made a small flat area in the column (and a thin, shallow groove) to accomodate the tool holder and screwed it in place with two large wood screws.

This allows me to easily switch from the Dremel tool to my Bosch router. I can also easily remove the Dremel tool from the holder.

The attachment works very well for me.

Don

[donframbach]

Here is the picture:


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[cwho@lgmmodel.com]

We have been using a Makita die grinder as the primary tool on our PR96. We mill only foam but in full 3d so the machine is on for say, 8 hours a time. We go through brushes on the Die grinder and it seems like a weak link - definately a "not designded for this purpose part of equation". I very much like the idea of using a air turbine tool as we have a 6.5 hP 80gal compressor that will do almost 17 SCFM at 100psi. Unfortunately we spin a 1" router bit on the hogging pass. Does anyone think this will actually work with an air turbine or sould we go to a columbo spindle. I like the idea of having more collet diameters and the narrow shaft of the air turbine will help us on our 10" Z's THoughts are appreciated.
Charles

[toys]

I love my air spindle. It cuts sooo smoooth and has the low maintenance of an air tool. I would call the folks at Air Turbine Tools, they can let you know what specific spindle/air flow requirements you would need for your application.

[rgbrown@itexas.net]

Anything capable of pulling a 1" bit will probably eat a LOT of air. I have 19 CFM @100 PSI and doubt I have enough air to supply a tool with that kind of power.

Ron

[toys]

Paul Campbell, I do have dust collection and I cut very small parts some are aprox 1x2" I'm using the air turbine discussed above. It is much better then the dremel because it has no torque. It cuts with shear speed. There is no torque to cause it to be lifted up and sucked away by the dust collection.

Don, I liked your mount for your dremel so much I made one for my airturbine only I cut 1/4" discs with a hole in the center for the turbine and glued them together. I put a cut through the side and two screws to hold the turbine inside the "puck".
It works great thanks for the insight.
I'll try get a picture soon.

[toys]

Here it is. There are also two air lines behind the airturbine that go through the "puck" with 90 degree turns coming out of the bottom. These help tons in increasing bit life.



Also notice the dust collector head is a giant jaw that opens up to allow easy bit change/cleaning.

[toys]

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[toys]

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[toys]

Does anyone know how much preasure a ansi 61 type L 3/4 copper pipe can take before bursting? I want to build a bigger better after cooler and wanted up upgrade my pipe but I'm afraid it will pop. Not conserned about schrapnel because it will be submerged in a 55 gallon drum. Just need it to work. Also I was planing on brazing on the fittings that are inside the drum. Would brazing be strong enough? I'm planing on at least 150 psi and possibly 175.

[harold_weber]

Found this by searching for burst +pressure +copper +tubing

{http://www.coppercanada.ca/pdfs/WhoSaysAdEng.pdf,http://www.coppercanada.ca/pdfs/WhoSaysAdEng.pdf (http://www.coppercanada.ca/pdfs/WhoSaysAdEng.pdf%2Chttp://www.coppercanada.ca/pdfs/WhoSaysAdEng.pdf)}

Looks like you would be OK, but to be really sure, you could use heavier wall type J or K.

Heat exchangers tend to fail from stresses due to: 1. mechanical vibration, and
2. stresses from thermally induced growth when the designer tried to rigidly hold everything so it does dot vibrate.

[sheldon@dingwallguitars.com]

David,

I really like the "jaws-of-dust" idea. How is the suction hooked up?

[toys]

Thanks Harold, I also found a site with specs. I've been trying to braze the joints but my little home brazing torch just dosn't have enough heat. I guess I'll bring it by a welding shop to see what they can do.

Sheldon I have a 3" pvc pipe that comes straight down on the other side of "Jaws" I had to do some slight modifications of my Y carrage to make it fit. The only trouble I've had is the jaws have become a little loose and won't stay shut. I need to put some sort of latch on them. Its been great for bit changes as nothing gets in the way. Next time around I'll probably make it square so I can quickly change bristle lengths for different work.

[sheldon@dingwallguitars.com]

David, two ideas that have worked well in the past have been bicycle quick release skewers and Nd magnets from Lee Valley. Just my .02

[toys]

I asked around and found out the air conditioners with the "new gas" have silver soldered copper and their preasure is 500 psi. So I took my copper tube to a radiator shop and had them silver solder it.

Sheldon thanks for the tips on skewers and Nd magnets.

[stevem]

This is the prototype air deflector I've attached to my Makita router. Will make these for sale to fit PC and Makita routers if there is interest. Attaches with hose clamp around router body. Projected price is $15.00. Made from ABS.


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