Right Angle Head on "Z" Axis

[steeve]

I have an ongoing product that requires several .020" wide by .050" deep slots to be machined in ebony boards. Slitting saw blades are available with the correct thickness. They are about 2 1/4" in diameter, and have a 1" arbor hole.

I was wondering if any Shopbotters have modified their machines to use this type of cutter?

[Wdyasq@yahoo.com]

Steve,

With the assumption(OOPS) you are going to use your ShopBot conventionally also, my first thought is to make a mount for an arbor on the 'Z' axis. This would be belt driven and the device would be high enough to never interfere with the router. To use the cutter, I would remove the router's bit. This would give enough clearance for the saw to cut. I would hope I could get the center of the cut to be the same 'y' number just for ease of use.

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]

Steve,

Why not use a small router bit mounted vertically?

I just cut a small sign with a 0.020" router bit from "Think and Tinker" BTW they sell even smaller bits!

http://www.thinktink.com

Don

[steeve]

Ron and Don,

Thanks for the tips. I originally tried cutting these slots with an .020" bit in my PC 3.25hp router, but the bits broke right away. I don't remember the feed speed, but I'm sure it was slow.

So, then I bought one of these .020" slitting saws, as I know this is how these fret slots are cut in the music industry. I didn't want to invest in building a 22 blade arbor saw, so I fitted a 4" right angle grinder to my ShopBot. I took the router off, as my Z-drive is still ball-screw, and I was concerned about the weight of carrying 2 systems on it.

I wrote a simple file to cut a bunch of these slots in some scrap ebony. It looks like the blade isn't holding up so good, and the slots seem to flare-out or widen a bit at/near the end of the cut. Tomorrow I will try running this same system with the aid of a router speed reducer, because the grinder spins at 10,000 rpm, which might be too much for this type of blade. However, I am concerned about losing torque at the spindle.

Donald, I have contacted the bit supplier you mentioned. I'm hoping they will get in touch with me on Monday.

Anybody else doing anything like this?

Steve

[donframbach]

Steve,

I used a Bosch router 1617 at slightly less than full speed (to make things quieter). I used a feed rate of .1"/second. I cut about .07" deep. I am thinking of getting a high speed air driven spindle so that I can cut faster. Actually, I was mistaking in my last post. I have .020" bits but I used a .015" bit for the sign (all bits from "Think & Tinker").

Hope this helps.

Don

[sheldon@dingwallguitars.com]

Steve,

It's pretty hard to get rid of the kerf flare at the end of a cut using such thin blades. One thing that helps is to use blade stabilizers that hold the blade as close to the work piece as possible. Also a hollow ground blade is important too as it is less prone to heating and binding.

The manufacturer of the blade should be able to advise you of the proper tip velocity for ebony.

[Wdyasq@yahoo.com]

Steve,

Sheldon just about covered the gamut with his post. I thought of the 4" grinder but was afraid of the speed. There are some light 7" 'sander/polishers' that have a ~2500 RPM speed and a High/Low switch. They have the same 5/8 thread and pitch as the 4" stuff. And as mentioned, blade stiffeners might help.

While we are brain-storming, how wide is the kerf on the new little battery powered panel saws? You might be able to find a local saw sharpener to reduce the set and/or change the grind for the type cut you need.


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

[steeve]

Hi Guys,

This is a great forum! I contacted "Think & Tinker" about bit options. Very knowledgable fellow there. I'm re-thinking this slot deal, and I'm going to try it with a conventional small dia. bit. The slot ends up being .025" wide, so I am going to try some of their bits at this size. My next ShopBot modification project is to mount an air grinder to the Z-axis. I have one that runs at 56,000 rpm and has an 1/8" collet. I was told by the guy at "T&T" that the ideal rpm for their bits is 40,000-60,000 rpm. My PC router tops out at about 22,000 rpm, so I guess it will get a chance to rest when I make these parts.

I already made a fixture to hold the right angle grinder. I think I can modify it to hold this (much smaller) air grinder.

Ron, I have a unistrut ShopBot (32" X32"). Would those wheels you just mentioned be a worthwhile upgrade from the original sliding door type wheels?

Steve

[David Fisk]

Steve, When I added BWC wheels to my ShopBots carriages things got smoother. Inspite of my ShopBots other ailments.

[steeve]

Thanks David,

I have an e-mail into ShopBot for some "Wheel-Upgrade" info. Still waiting for a reply...

I just noticed that the Z -Axis wheels on my ShopBot are different from those on the X & Y axes. X &Y have wheels that have a sort of a "W" profile on the outer edge. The "Z" axis wheels are just a simple convex radius. I used to use sliding door hardware from a company called Slide-Co. These wheels look identical to those.

I'm wondering if my X &Y wheels are the most current? Also wondering if I should update the wheels on the Z?

Steve

[David Fisk]

Sounds like you have the BWC wheels on your xy. Take a look at their website and you can see what they look like and then you'll know for sure. www.bwc.com