PRS Standard

[dan78]

Hi guys,
I just receive my SB Standard, and start to set him up ;o)

I would like to ask , how are you guys disconnecting the motors on PRS Standard control box. The cables came from the box pre-mounted for the motors, if you have to troubleshot the square of the table, obvious is a no go for moving the gantry with the motors hooked on the control box.

What are the steps what you are doing to disconnect the motors.

Cheers DAN

[Brady Watson]

The motor cables disconnect from the motor side. It is not advised to disconnect them from the control box where they connect inside. When you wire it up, you'll run the spindle, spindle fan, proximity switches and Zzero plate TO the control box (and VFD) & You'll run the motor cables FROM the control box to the motors.

It certainly makes wiring more difficult than it should be, but it isn't too bad if you are neat and organized - which means you are adding to the reliability of your tool by making sure none of the wires get snagged etc. Be sure to keep the wiring neat and add zip ties to keep wires secured.

-B

[dan78]

Thank you very much for your fast answer ;o)

I was not very clear with my question , but you nailed right ;o)

Basically if later a problem will require to unplug the motors ...we need to cut the protection foil to unplug the motors. Or to troubleshot any problem with the gantry with the motors down from the track.

Please let me know how you deal with a problem like that ;o)

Cheers DAN

[Brady Watson]

...we need to cut the protection foil to unplug the motors.

Dan, I am assuming that you mean shrink tubing ? Then, yes...carefully cut it away, do what you need to do and re-shrink. If you wire things correctly and give yourself some extra slack where it is needed (like wrapping once around the Y motors to allow for pinion replacement & zip tie the wire to the motor) then there isn't much to really worry about. Worse case, you just unplug the motors.

-B

[dan78]

Yes , you are right ;o) I was thinking to shrink tubing ;o)

Okay then , tomorrow I will connect the motors, and the control box, and give a run to hear how sounds ;o) maybe I can do even same dust ;o)

Just to double check , how are you felling the gantry when push with the motors engaged. Is moving relatively easy, not that easy for my wife ;o) , I can not fell any bumps is going pretty well all the way, but I just want to make sure is not to tight, I could read on other thread about problems if the motors are engaged to much.

Thanks again for you fast answers ;o)

[Brady Watson]

Engage the motors as tightly as you can into the racks. Lift and rock the motor into mesh with the rack and tighten the screws down. 'Too tight' is for the older PRT models.

Try not to move the gantry or Y or Z around too much with the motors plugged into the box. The motors become generators and you can damage the motor drivers if you generate too much voltage by pushing by hand. If you MUST move it by hand, either drop the motors out of mesh with the racks or move very slowly.

-B

[dan78]

Okay , and again many thanks ;o) I will let you know how go later ;o)

Cheers DAN

[dan78]

Thanks for help Brady , including this

" Reverse the green & black wires in either end of the Wago connector on EACH X axis. Make sure control box is OFF. "

from a different thread ;o)

My PRS Standard is up now I will buy next week same cheap bits to see how I can do something ;o)

[dan78]

Okay ...I manage to have all done and start.

I start cutting with a very large rectangle to check the diagonals.

First try I have a error of 3mm, stop all, push up and down the gantry , connect again the motors , power , zero , and again a very large rectangle , x,y 30,30 the other corner x,y 2200,1150, and this time I have a 2 mm error on the diagonals.

How precise are you when you try to check the square of the table ?

Test on the 30, 40 inch until you have both diagonals exactly 50 ?

Are you happy with a error under 1/8 inch ? which would be close with 3mm ?

[steve_g]

Dan

You should be able to get closer than you can measure by hand... There are some other items that can cause mis-cuts, #1 being bit deflection. I don't know what bit, speeds, depth of cut, or cutting strategies you used to know if this might be an issue.

Something some of us do is (me anyway) pull the gantry back against the stops while turning the machine on... This racks the gantry square and the steppers hold it that way. This method only works after some initial fooling around micro adjusting the stops.

Disclaimer... I have a PRT Alpha and am not familiar with the nuances of the PRS standard...

SG

[dan78]

Hi Steve,

Thank you for you fast answer.

I am using a bit made here in NZ , the first on this list from the producer web page.

http://www.linbide.co.nz/product.php?p=1

I think I get the picture, I will do few more cuts, and make another similar test with a bit design special for a CNC router ;o)

The speed what I have used was 1600 with 3 ips and I was going deep 1.5 mm on the table, because is not yet surfaced, just a simple rectangle and measure the diagonals. With this settings I manage to make pretty nice chips on MDF, I think they could or should be a little bit big...but for the first cut I was happy with that ;o)

I will use this tip with the stops , but I have to set them now, so I can trust them first time ;o)

Cheers DAN

[steve_g]

Dan

If I understand you correctly... your test cuts are being done with an 1/8" bit. This bit is very susceptible to deflection due to cutting load. Next time you cut a test rectangle, cut in climb cut mode allowing about .020" on an inch. Follow this up with a conventional cut full depth on with no allowance. This will result in a clean cut that had a very light load on the bit.

SG

[dan78]

Yes that is correct, I will re-do the test tonight NZ time following your advice.

What is a result what you will consider okay ? Would you accept any marge of error ?

Thanks again for your fast answer ;o)

Cheers DAN

[steve_g]

Dan


"What is a result what you will consider okay ? Would you accept any marge of error?
The more work you put into doing this now, the better results you'll have from now on. If your main business is cabinetry, I would work on it until I can't measure any difference. If however you are doing only 6" X 24" cabin signs or 6" X6" 3D relief carvings... forget the small stuff!

SG

[dan78]

Okay , then i will try to make the diagonals equal.

Many thanks again for the fast answers, I will be back with the result tomorrow ;o)

Cheers DAN

[garyc]

Dan....
Look in the HELP Menu [H]elp [S]quaring the X car

More info here: http://www.shopbotblog.com/index.php/2008/12/tuning-up-the-prs-gantry/

You should take the time to get it perfect, as there is no reason not to. These machines are capable of a couple thousandths accuracy, why not take advantage of it?

Learn the fine points of a proper assembly, tuning and maintenance and you can be rewarded by the machine for many years to come.

[dan78]

Thanks for your advice guys ;o)

I have followed Steve's advice last night, and the results are GREAT !!!! I still can see a difference, just because I think I am a bit extreme ;o) The difference now between the diagonals are down to 0.5 under 1 mm , which I think is great, that error can be easy introduced by the tape measure.

Today I plan to finish the table, and surface, once that is done I will do the test what Gary explained on this how-to, I have already read I think 20 times the steps ;o)

I will let you know what are the results.

Thanks again for helping me to understand what I should make a standard ;o)

Cheers Dan

[dan78]

Hi guys,

I will write here with another problem …

The very beginning now is gone …and obvious for a very nice cut …very important to secure well the material on the table.

Actually after only 4 weeks ….seems like the most time consuming part is making strategies to secure well the material on the table, screw on the best location and make sure you don’t hit a clamp ( yes , I did it ;o) LOL )

Obvious the next question now “vacuum system” .
Lots of stuff on the forum, I would like to ask an opinion from you guys about this.

http://www.vabs.co.nz/side-channel-blowers/289-scl06-02kw1p.html

Here are the details
FPZ SCL K05-MS single stage side channel blower
1.5kW 230V single phase 50Hz electric motor
Displacement 219 m3/hr
Pressure to +17.5 kPa
Vacuum to -17.5 kPa
And something what is not for me in this stage,

http://www.vabs.co.nz/dry-claw-vacuum-pumps/311-vcx100-22kw.html

which I am sure is …a…great solution , but the price is about 10 times bigger than the first one ….out of discussion for now ;o)


To be more specific all what I can have for now is the first one, and I am curious to know if somebody who already done the “vacuum system” can look to the specs and have an opinion about how good can be or not the first pump.

Thank again for you help.
Cheers DAN

[billp]

Dan,
I'm not familiar with those units of measurement, but if the kPa stands for "kilopascals"than my conversion program says that means this pump can only pull 5.16 inches of mercury ( which is how most people will be measuring their vacuum capability for tables such as you are planning). A standard Shopvac type canister vacuum will pull about 4 inches of mercury for comparison.

[dan78]

Okay ...

Basically is not much than a "shopvac" ...only bigger and noisy , I still need about 4 of them to make something decent ...

[dan78]

Hi guys,

Vacuum again ;o)

Would you like please to look to this pump specs, and let me know what you think.


http://www.vabs.co.nz/side-channel-blowers/284-scl06-02kw1p.html


FPZ SCL 15DH two stage side channel blower

0.55kW 230V single phase 50Hz electric motor

Displacement 50 m3/hr

Pressure to +30 kPa

Vacuum to -27.5 kPa


That would be close with 3.988537788 PSI......


If you already have done the vacuum table, would you use a pump like this ?

P (1) Δp (2) Q (3)
kW mbar psig m3/h cfm
COMPRESSOR
A 50 Hz - 2900 rpm
0.37 50 0.72 90 53
0.55 150 2.17 70 41
0.75 250 3.62 52 31
1.1 350 5.07 35 23
1.5 400 5.80 26 15
B 60 Hz - 3500 rpm
0.9 225 3.26 84 49
1.3 350 5.07 64 38
1.75 450 6.52 46 27

[dan78]

For who would may be interested to know.

My initial question to this post was related to the motors, and Brady help me to figure out how things are there, thank you very much again for that help.

Then my next problem , was related to how square is the table, because I could se on large rectangles a 2mm difference on the diagonals.

Long story short, initially I can not figure out from where came that error, ant I learn to live with that ….basically can not be seen , but I know is there …
Until I make a “next step” , and I have done a plaque using a V-bit cutter , on that process I have notices the “Z” axis is having a little movements in some directions , I could see it just watching the V-bit cutting , Stop, and checked all again , and I have found the “Z” car having a bit of movements because I have not tide properly the down eccentric bearings . Tide the bearings to remove any movement , start again , the movement disappear , redone the large rectangle test and the diagonals are now equal ;o)

Thanks to everybody for giving his input, and help me to fix this problems.

I am still having the vacuum a project to be done, and a opinion about the pump what is above would be very appreciated ;o)

Cheers DAN

[Brady Watson]

Dan,
The pump listed above has the following specifications:

8.12 inches of Mercury
29.4 cubic feet per minute (CFM)
0.74 horsepower

This is a small pump - and is not worth buying for your CNC. You can put together a very affordable and useful vacuum hold down system ($150 or so) by using a Lighthouse Brand (http://www.centralvacuummotor.com/lighthouse.htm) vacuum motor and a BradyVac vacuum plenum from a single sheet of ultralight MDF or Trupan.

Several years ago I shared my vacuum research with this forum The 9-15 - Open Source Vacuum Project (http://www.talkshopbot.com/forum/showthread.php?t=545) with the idea that others would take my research and make it into something a bit more polished. Gary Campbell did a fantastic job with his Black Box Vacuum Source (http://www.talkshopbot.com/forum/showthread.php?t=11813) as did many others. It is hard to beat the Lighthouse motors for getting into the vacuum game. Several people use these on a production basis, but they really are not designed with the same duty cycle in mind as a bonafide vacuum pump, that operates at a much lower RPM with much tighter tolerances.

Take some time to check out the links above and do some more searching on this forum to give you some ideas and examples of what others have done. Also, check the For Sale & Wanted (http://www.talkshopbot.com/forum/forumdisplay.php?f=12) section since good pumps suitable for CNC machining pop up for sale from time to time, like this one (http://www.talkshopbot.com/forum/showthread.php?t=15712).

-B

[dan78]

Hi Brady,

Thanks again for your fast answer, I have already a read on this projects, and I will have a bit more.
The problem is I am here down under in Gordonton New Zealand , and if you guys have difficulties sourcing stuff …do not ask us ;o)
I would like to go for something like this “Lighthouse Brand” vacuum motors for the price, the challenge is to find them here if I can.
What would be something what will work ? if I take this like “reference “ where I should be , to be okay ? (on the budget … I can find here “Becky” but I can not afford in this stage ;o( )


8.12 inches of Mercury =? To be okay
29.4 cubic feet per minute (CFM) =?
0.74 horsepower =?

Thanks again , and for the “ramping” article good stuff ;o)

Cheers DAN

[dan78]

So if I can find something close with 190CFM ..that would be a good start ?

[Brady Watson]

Dan,
2 Specs are the most important:

CFM range between 90-200 (higher number = more airflow)

Suction range between 8-12 Hg" (higher number = more suction)

Find what you can locally...and you may be able to get a Fein Turbo III vacuum near you. It does something like 125 CFM & 8.2Hg" - but they are pricey & you would want multiple ones. I've used one for years...it's more important HOW you use the vacuum you have than the vacuum you have itself.

-B

[dan78]

Thank you very much for you answer, I will have a look around, and once I find something what I think will work I will try to ask again your opinion. ;o)

Cheers DAN