CNC Router with THK KR46 actuators Finished! pics & video

[wisp]

Originally Posted by gdc Depending on moisture a butcher block may expand as much as 3/16” (assuming that your table is maple).

I called Michigan Maple Block, the mafg of the table top, they assured me I should have no trouble with expansion, or warping. yeaee! They say its sealed top/bottom & ends. Here is a quote from their page,

"" A special Wood Welded wear-resistant finish is then applied - DURAKRYL 102. This tough, acrylic coating will repel alcohol, bleach, even paint thinner! Wood Welded Butcher Block is one of the few materials that can take so much hard wear and tear, be resurfaced or repaired without any special tools or particular skill, and come up looking as great as ever. ""

I was thinking of drilling a large hole pattern in the table for workholding, and then pressing threaded metal inserts in the holes from the underside, that way they couldnt be pulled out. Has anyone done this before?

[Cold Fusion]

I've experimented with inserts in a wood base and I can tell you that it just doesn't work as well as an aluminum base. After many problems with mine expanding and contracting, I finally bit the bullet and bought a 6061 base that I could tap a grid of holes into. It's a world of difference.

[ViperTX]

Wisp,

For workholding I don't see any problem with that approach unless you're leaving something clamped for long periods of time....ya know through the expansion/contraction cycles of the top.

[chuckknigh]

Originally Posted by wisp I called Michigan Maple Block, the mafg of the table top, they assured me I should have no trouble with expansion, or warping. yeaee! They say its sealed top/bottom & ends. Here is a quote from their page,

Wouldn't drilling all those holes "break the seal" and allow expansion and contraction? The only reason it's stable now is because it's encased in acrylic plastic. Worse yet, it'd just be holes in 1 side, so differntial expansion would probably cause it to cup.

If you put a sealer on the inside of the drilled holes, though, it'd probably keep it stable.

-- Chuck Knight

P.S. Your machine is absolutely beautiful.

[zoltan]

I have a question for who can help - how do you syncronize those two axis in the case X? What kind of wiring diagram or do you use a different type of stepper driver, or you just connect in parrallel the two steppers?

[zoltan]

Wisp,

Do you think that if I buy three actuators of 475$ you can ship them in Romania to me? Can you give a pm to discuss this subject?

[gdc]

Originally Posted by wisp I called Michigan Maple Block, the mafg of the table top, they assured me I should have no trouble with expansion, or warping. yeaee! They say its sealed top/bottom & ends. Here is a quote from their page, "" A special Wood Welded wear-resistant finish is then applied - DURAKRYL 102. This tough, acrylic coating will repel alcohol, bleach, even paint thinner! Wood Welded Butcher Block is one of the few materials that can take so much hard wear and tear, be resurfaced or repaired without any special tools or particular skill, and come up looking as great as ever. "" I was thinking of drilling a large hole pattern in the table for workholding, and then pressing threaded metal inserts in the holes from the underside, that way they couldnt be pulled out. Has anyone done this before?

I don't really think they can guarantee there isn't going to be any expansion. I've been doing woodworking for 30 years. Wood will always expand. It may not expand much, but it's going to regardless of how much you seal the wood, especially when you're using solids.

But if you do decide to risk it, make sure to seal any holes you make. If the wood fibers have access to moisture, you'll eventually have expansion, albeit minimal.

You mentioned using screw inserts. They do work well. They're tricky to get started and more so in a hardwood. Good luck to you.

[pminmo]

I too have been woodworking for over 30 years. You have several things going for you: Hard Maple is a very dense wood, the laminations of multiple slices gives a ton of strength, and makes it less apt to warp and dimensional variation. ALso the fact that it is sealed. If you put it in an enviornment that is fairly tmeperature stable and humidy stable you will help yourself. But I seriously doubt it will stay as stable as your bearings. If you want to maintain the accuracy that you have invested in your parts, slap some steel bar on the the top of the wood.

Phil

[wisp]

Originally Posted by zoltan I have a question for who can help - how do you syncronize those two axis in the case X? What kind of wiring diagram or do you use a different type of stepper driver, or you just connect in parrallel the two steppers?

I am using API 3535 stepper drives. The two drives running the Y axis motors are both wired to the same pins on the breackout board. I had originally planned to use one motor with a timing belt running to the other actuator, but I wanted to try running two motors in sync first, as I already had the motors. So far I have had no problems with the motors loosing sync. They are rated 540oz, wich is overkill for this setup, so I have the amps turned down to 1/2 the motor rating as it makes the motors run smoother.

[wisp]

Originally Posted by zoltan Wisp, Do you think that if I buy three actuators of 475$ you can ship them in Romania to me? Can you give a pm to discuss this subject?

For those interested, I have put some photos of the KR46 actuators I have available up HERE

And here is a link to a PDF file with full specs.

I also have some Nema34 motor mounts made by THK, for KR46 actuators, they are $16 each there is also a picture of one.

And if anyone is interested, I can make X-Y gantry kits to allow you to bolt three KR46 actuators together the way I did for $60.

Also, what do you guys think would be a reasonable price for brackets to hold porter cable/makita, etc.. routers like the ones in the photos? Or brackets for RotoZip also. They would be precision machined from solid aluminum. I know these brackets can be tough to make if you dont have access to the proper equipment.

Thanks for the complements and advise on the router table also.

[wisp]

Hey all, just an update on the maple table flatness/warping concern. I ran an indicator over the whole table again, I did this also when the router new> and it is reading .02" max out of flat, the same as the first check. It has been in the garage for over 8 months now, in Houston heat/ humidity, and has shown no detectable sign of expansion or warping, so far.

Unless some crazy wood warping action happens in the next 4 months, which will mark one year since the router was assembled, I would say any concern over using a laminated wood table are unfounded. It has been a VERY stable, flat and rigid surface for me in the last 8 months.

I will check it again in a couple months, if it starts to show any warping, I will post it.