[cromag27]

rather new to cnc routers and i'm needing some help. i cut a lot of small acrylic parts that need to be cut-through. i've been using super 77 to hold the pieces down, which worked great........the first time. now my spoilboard is well, spoiled, and the pieces aren't holding very well. haven't tried double sided tape so i don't know if that would hold any better (i'm thinking not). don't want to cut tabs because of the time needed to hand trim all of them off. right now i have to manually hold each piece on the final pass to make sure it doesn't move. defeats the purpose of a cnc.

one issue is that acrylic sheets are nominal and not the size as advertised (1/2" is closer to .472, 1/4" is closer to .236, etc), and there can be slight variances from sheet to sheet. so i guess first step is to do test with each thickness to get the cut-through just right. didn't do that the first time around.

any help/suggestions regarding spoilboard care and usage would be appreciated. thanks!

*** sorry about the spelling error in the title, apparently "spoilboard" is one word. ***

[ger21]

1) surface your spoilboard so that it's smooth and flat.
2) Zero the Z axis to the spoilboard, rather than the top of the acrylic.

[ubergeekseven]

I am new to this as well, but have been furiously reading and testing. I flattened my bottom spoil board and drilled holes for threaded inserts. Then i put the inserts in from the bottom of the table because they have a lip on them and in the bottom, if needed, i could still surface the table. Then i put another piece of mdf on top with the same drill pattern and a oversized hole with a resting spot for bolts to attach to the table below. Then, i surfaced that board. Now i have a board that i can go into without worrying too much.
You could just put a cutoff of mdf and flatten it. Then you can mount on the smaller work surface and cut through it all day and scrap it.
You could try to cut a pocket for the work to be set into. With a Mickey ear on the corners to allow you to pick it up. Then try to tape it inside the pocket.
If the stock is thick enough, you could wedge it in to the pocket without bending the stock. But your cut through, without tape, would need tabs.
Hopefully others chime in on this too, i haven't tried acrylic yet. So having some tips from experienced people would be great.

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[Jim Dawson]

Sounds like you are setting Z zero at the top of the part, try setting Z zero at the spoil board. That way the material thickness doesn't matter, within reason of course. I have successfully used carpet tape.

Sounds like you are buying inch size sheets, and they are shipping metric

[cromag27]

1) surface your spoilboard so that it's smooth and flat.
2) Zero the Z axis to the spoilboard, rather than the top of the acrylic.

two things i'm reading up on right now. made a mistake by not surfacing it to begin with. got anxious to try it out! i usually use onsrud bits and i see their spoilboard bits are like $400. hoping those are overkill for me and i can find cheaper options. i have a feeling i'm going to need to laminate several sheets of mdf (right now i'm using 1/2") and surfacing over and over.

i'm using an nwa hd3 so i need to figure out how to z0 to the board with their software.

thanks for the reply!

[cromag27]

i thought about using nylon screws/bolts from the bottom to hold it down. bits will cut right through nylon if need-be.

I am new to this as well, but have been furiously reading and testing. I flattened my bottom spoil board and drilled holes for threaded inserts. Then i put the inserts in from the bottom of the table because they have a lip on them and in the bottom, if needed, i could still surface the table. Then i put another piece of mdf on top with the same drill pattern and a oversized hole with a resting spot for bolts to attach to the table below. Then, i surfaced that board. Now i have a board that i can go into without worrying too much.
You could just put a cutoff of mdf and flatten it. Then you can mount on the smaller work surface and cut through it all day and scrap it.
You could try to cut a pocket for the work to be set into. With a Mickey ear on the corners to allow you to pick it up. Then try to tape it inside the pocket.
If the stock is thick enough, you could wedge it in to the pocket without bending the stock. But your cut through, without tape, would need tabs.
Hopefully others chime in on this too, i haven't tried acrylic yet. So having some tips from experienced people would be great.

Sent from my SM-N920V using Tapatalk

[cromag27]

that's just how acrylic sheets are measured/sized. at least until you get up to around 1 1/4" then it matches. there are some variables likes type of acrylic and manufacturer.

general acrylic thicknesses:

0.236 = 1/4"
0.354 = 3/8"
0.472 = 1/2"
0.591 = 5/8"
0.708 = 3/4"
0.944 = 1"
1.250 = 1.25"
1.500 = 1.5"
2.000 = 2"

Sounds like you are setting Z zero at the top of the part, try setting Z zero at the spoil board. That way the material thickness doesn't matter, within reason of course. I have successfully used carpet tape.

Sounds like you are buying inch size sheets, and they are shipping metric

[ubergeekseven]

i thought about using nylon screws/bolts from the bottom to hold it down. bits will cut right through nylon if need-be.

That's a great idea! Nylon washers too. If more coverage is needed.

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[cromag27]

https://www.woodcraft.com/products/6...-bit-1-4-shank


any feedback on this?

[ubergeekseven]

https://www.woodcraft.com/products/f...1-1-2-d-1-2-cl

any feedback on this?

I'm using a similar one. https://www.amanatool.com/rc-2249-in...outer-bit.html

I messed up the first sides of the bit when attempting flattening. Totally my fault, inexperienced. But, i have successfully flattened my board now and it's great. I bought replacement knives and glad i got the insert over the fixed one. I would have spent more after messing up the first time.

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[cromag27]

$175, not too bad for a good investment.

how did you mess up? i don't want to do the same thing. haha.

I'm using a similar one. https://www.amanatool.com/rc-2249-in...outer-bit.html

I messed up the first sides of the bit when attempting flattening. Totally my fault, inexperienced. But, i have successfully flattened my board now and it's great. I bought replacement knives and glad i got the insert over the fixed one. I would have spent more after messing up the first time.

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[ubergeekseven]

$175, not too bad for a good investment.

how did you mess up? i don't want to do the same thing. haha.

I took too late of a cut at too high of a speed. It burned the board and plunged in and chipped the edge of the inserts. I just turned them and adjusted my settings. I now take .15 off. But I'm using a router, not a spindle. So i set it to the highest setting and move at 125ipm.

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[ger21]

To surface the spoilboard, just buy the largest two flute straight bit you can find that will fit in your spindle.

[ger21]

I think that this new Amana bit is a better choice. I plan on picking one up soon.
https://www.amanatool.com/rc-2255-cn...outer-bit.html

[ubergeekseven]

I think that this new Amana bit is a better choice. I plan on picking one up soon.
https://www.amanatool.com/rc-2255-cn...outer-bit.html

That looks like a nice bit. Also gives you the ability to chamfer. I can only flatten or clear large areas.

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[cromag27]

around $180, not bad.

unfortunately, the spindle that came with my nwa hd3 only accepts up to 1/4" shanks.

I think that this new Amana bit is a better choice. I plan on picking one up soon.
https://www.amanatool.com/rc-2255-cn...outer-bit.html

- - - Updated - - -

i like the ability to replace the blades. saves money or gimmicky?

To surface the spoilboard, just buy the largest two flute straight bit you can find that will fit in your spindle.

[ger21]

You can buy a 1" 2 flute straight bit for $15, which is about the same cost as replacement blades on an insert cutter.

[ubergeekseven]

You can buy a 1" 2 flute straight bit for $15, which is about the same cost as replacement blades on an insert cutter.

I just bought the Replacements. Mine has 2 different inserts. By themselves they are about$8 each. Buying 10 drops them to $5. Each insert has 4 edges. So if you count the edges, a full replacement would cost $5 each time you turn them. The biggest thing is that you can quickly get back to running by switching out turning them. You could just buy a handful of the regular bits though and have the same capability.
I bought regular bits for must of my others for practice. Then I'll upgrade to insert bits once i see what i use the midst in the long run.
Anger nice thing, the inserts may be the same across multiple bits. I would say that if you have several with the same, it will cost less in the long run. They also sell bits with the ability to change the angles so that it can be configured in multiple ways.

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[cromag27]

thoughts on the actual spoilboard itself? 1/4"? 1/4" x 2? 1/2"? 1/2" x 2?

[Jim Dawson]

I normally use 3/4 inch MDF. You can surface it many times before replacing.