CNC router 'waste board' suggestions?

dkmc · Aug 28, 2022

Not new to CNC but new to CNC wood routers. Any suggestions as to what would be a good sheet material for use as the platen waste board would be appreciated. Not familiar with trade names, ie MDF, etc. Obviously it needs to be fairly precisely flat, I prefer not to have to surface it as the parts in my project are all 'thru hole' with no very precise depth requirements, but 'flat as practical' platen from box store is my goal.

TIA

whateg0 · Aug 28, 2022

MDF is cheap and flat. Also very dense. If you glue up a couple layers of it and are careful to mind your cut depth, you can resurface it several times before needing to replace it.

One thing worth mentioning is that it's prone to a bit of tearout, so be prepared to dress those edges before the next workpiece is clamped it screwed down to it. That includes where your hold down screws go in. If you don't do that your next workpiece may not be flat on the spoil board.

macgyver · Aug 28, 2022

Are you using vacuum to hold down, or just screwing the parts down? Honestly, either way an MDF product is going to be the best bet but if you are running a low power vac pump and really need to maximize the efforts then you can get a LDF, or low density fiber board vs medium density, it will flow more vac through the board which makes for better holding power. The other thing to do if using vacuum is to face the mdf to cut the skin off, it makes a difference to flowrate.
I have never had a reason to use the LDF myself, if I get to the point where I might need to do that I'll cut channels and place an O ring gasket in it instead.

As for flatness, even cheapish HD or Lowes mdf is pretty flat and consistent thickness. Only reason to do anything to it before using is if you need to pull vac through it.

dkmc · Aug 28, 2022

macgyver said:
Are you using vacuum to hold down, or just screwing the parts down? Honestly, either way an MDF product is going to be the best bet but if you are running a low power vac pump and really need to maximize the efforts then you can get a LDF, or low density fiber board vs medium density, it will flow more vac through the board which makes for better holding power. The other thing to do if using vacuum is to face the mdf to cut the skin off, it makes a difference to flowrate.
I have never had a reason to use the LDF myself, if I get to the point where I might need to do that I'll cut channels and place an O ring gasket in it instead.

As for flatness, even cheapish HD or Lowes mdf is pretty flat and consistent thickness. Only reason to do anything to it before using is if you need to pull vac through it.

Clamps no vacuum

DDoug · Aug 28, 2022

dkmc said:
Clamps no vacuum

That sucks......

How about something like ceiling tiles ?
Provided the clamps are outside the tiles.

dkmc · Aug 28, 2022

DDoug said:
That sucks......
How about something like ceiling tiles ?
Provided the clamps are outside the tiles.

MDF will probably be fine. And clamps should work well. Work piece material is phenolic, 1/8 and 1/4" thick. Largest parts are 12" OD.

whateg0 · Aug 28, 2022

DDoug said:
That sucks......

No. No vacuum. No sucking!

Pattnmaker · Aug 29, 2022

We almost always screw jobs down because most jobs are hours of surfacing. We tried mdf early on but found it's too easy to strip screws especially as the boards get older. We get way more life out of Baltic birch plywood. It does need surfacing as thickness is often not perfect one end to the other.
Unfortunately the new Chinese Baltic substitute only comes in 4x8s rather than 5x5s which isn't great for a 5x10 table. Luckily I still have 2 lifts of 5x5s

stephen thomas · Aug 30, 2022

Atlantic Plywood, LeRoy.

MDF Archives - Atlantic Plywood

We offer a large selection of MDF options. From Georgia Pacific, Roseburg, Arauco, Weyerhaeuser, with more lumber and millwork.

www.atlanticplywood.com

Best, flattest, heavy. As has been noted, screws hold "OK" but easy to pull with multiple use.
Usually used with vacuum 'cause vac will pass through a sheet and hold. Kind of like partial strong mag on an electric chuck depending how areas between parts are masked off..

Import Plywoods Archives - Atlantic Plywood

Our import plywoods sample Products Include: Meranti - Chinese - Aspen - Indonesian/Malaysian - RussianSouth American - Radiata Pine Many More!

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No experience with the new Chinese birch. Still have some Russian.
Birch microlam is going to be the best option for screws Dunno how flat or parallel the new stuff is. Russian varied in absolute thickness ("calibration") but it was fairly parallel.

Stuff used to be cheap, not so much anymore!

You've got a tax#, can probably get product on Willcall.

If you only need a couple Sq ft, there's some here you can have to play with.

stephen thomas · Aug 30, 2022

PS: When parts need to come apart and go back together multiple times, i've put threadserts in either product, for machine screws. Should be easy on a cnc.....

richard newman · Aug 30, 2022

dkmc - how many parts do you need to make, and are you in a hurry to make them?

MDF would be ideal other than the long term screw holding issue. I'm not a big fan of sheet products, but MDF is pretty nice stuff - flat, smooth and accurately dimensioned. Baltic birch (generic term to me) is really strong and durable, but never flat in my experience. Atlantic is a good source, has different varieties, and my illusion is their stuff is higher quality than box stores. They also have a rack of hardly damaged stuff for bargain prices - once got 4x8's of 1" Baltic birch for $18/pc!

dkmc · Aug 30, 2022

richard newman said:
dkmc - how many parts do you need to make, and are you in a hurry to make them?

MDF would be ideal other than the long term screw holding issue. I'm not a big fan of sheet products, but MDF is pretty nice stuff - flat, smooth and accurately dimensioned. Baltic birch (generic term to me) is really strong and durable, but never flat in my experience. Atlantic is a good source, has different varieties, and my illusion is their stuff is higher quality than box stores. They also have a rack of hardly damaged stuff for bargain prices - once got 4x8's of 1" Baltic birch for $18/pc!

Richard, I have an open PO, just brought the Router back from PA Friday and need to deal with electronic adjustments/setup, so by the time I get going, it will be an ASAP situation I'm sure. I just need 'good enough' for now, there will be time for improvements on down the road I think. The local Lowes/Home Despot prob. makes the most sense right now.

SMT, I was thinking about threaded inserts for a longer term solution, seems like a good idea.

richard newman · Aug 30, 2022

What machine did you get?

Mine is an old Techno Davinci, tiny, 12" x 10" work envelope, but well built, heavy, and accurate. I have a solid alum t-slot plate with a 1" cc grid that I put in. 1/4" dowel holes on top, 1/4-20 threaded underneath, useful for tiling. Just use it for making banjos, almost big enuf....

dkmc · Aug 30, 2022

richard newman said:
What machine did you get?

Mine is an old Techno Davinci, tiny, 12" x 10" work envelope, but well built, heavy, and accurate. I have a solid alum t-slot plate with a 1" cc grid that I put in. 1/4" dowel holes on top, 1/4-20 threaded underneath, useful for tiling. Just use it for making banjos, almost big enuf....

Gerber 48x48. PPO retrofitted it with Linuxcnc and a China 3hp water cooled spindle. It's still open loop stepper motor driven, that may change at some point. I have enough parts laying around to convert to closed loop servos if warranted. Don't have a manual, but the structure 'figured up' to about ~1600lbs. T slot 'slats on this one, which probably means I only need strategically placed thru holes and no need for threaded inserts? Haven't focused my thinking on it yet...spinning several 'plates on sticks' lately.

macgyver · Aug 30, 2022

I'd start with mdf, drill the thru holes and put a stud in a T nut with whatever you need on top like a strap clamp or just flat washer and nut if the you have the clearance for it.

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CNC router 'waste board' suggestions?

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