Clean cuts in Russian birch

1153 Views 14 Replies 6 Participants Last post by Afish, Dec 10, 2021

Afish

Discussion Starter · Dec 7, 2021

I'm getting some fuzziness in the middle of the ply's when cutting plywood. lt looks to be right around where the up and down flutes on the compression bit meet. Any tips for getting rid of it for less sanding. I was using a .25" Whiteside compression bit, cutting 1/2" Russian birch at about 150ipm in 2 passes, climb cut, vectric aspire.

Typically its not a big issue and I just quickly sand it off. However I did some cutting of negative letters and it was much more unpleasant getting in there with some small files and cleaning it up. I would like to avoid this in the future as much as possible.

I was wondering if anyone has some toolpath tips for the cleanest cuts in plywood. I was thinking of trying to do a separate last pass. Not sure if I should do conventional first then reverse for the last pass or climb cut first and finish with conventional. Thats what Im thinking of experimenting with next time but was hoping for a good starting point.

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UglySign

· #2 · Dec 8, 2021

Fish,
Post some pictures! How big are these letters?

Afish said:
lt looks to be right around where the up and down flutes on the compression bit meet..... cutting 1/2" Russian birch at about 150ipm in 2 passes

Have you tried going 1 pass? 1/4" will cut 1/2" (12mm) no problem. Give it a try. Have extras on hand
in case you break any. Sending a compression in 2 passes (halfway) seems silly to me. The upcut part would
pull up the top grain and the downcut really doesnt have any cutting action to smooth the top edges.
Least thats what happened a long time ago for me. Just ramp it in one pass. Your middle part should be smooth.
Sometimes you can get a rogue grain band. Clean the bits after a few uses helps out also.

What machine are you using?

@4DThinker recently had a post on Optimizing CNC job for speed - A good read and he's using a 3/16" comp
as well as I do. 1 pass.

@difalkner has the video doing top speed on his machine cutting the BB Longworth chucks. Love how he reacts to it.

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difalkner

· #3 · Dec 8, 2021

Afish said:
I was using a .25" Whiteside compression bit, cutting 1/2" Russian birch at about 150ipm in 2 passes, climb cut,

I'm cutting 12mm BB with the same bit in one pass at 175ipm and it's a very smooth cut. Go ahead and do it in one pass and see how it works for you. (I'm making the assumption that your machine is robust enough to do this in one pass)

Afish

Discussion Starter · #4 · Dec 8, 2021

the first pass was around .35 so the downcut portion was contacting the top veneer. The top and bottom were fine the fuzziness happened in the middle. Its like right where the up and down cut portion of the bit meet are getting left behind. I will try doing one pass and see if that helps. Its a good (Whiteside bit) so I dont think its a bit issue. More of either a technique or plywood issue.

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Afish

Discussion Starter · #5 · Dec 8, 2021

Its a 4x8 import machine but yea It should be fine, It has a 4.5kw ER32 spindle, servos and upgraded HD linear rails.

@difalkner are you cutting conventional or climb?

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Afish

Discussion Starter · #6 · Dec 8, 2021

Part of the reason I was doing it in 2 passes is some of the cutouts are big enough to become projectiles. I was cutting clothes hampers so there is a lot of holes and nothing for the vacuum to hold onto. Since there was more holes than wood I was letting the machine make the first pass and following behind with some screws so it would be held down for the second pass

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difalkner

· #7 · Dec 8, 2021

UglySign said:
@difalkner has the video doing top speed on his machine cutting the BB Longworth chucks. Love how he reacts to it.

It's been a while since I've seen that video so it was cool to watch it again. We're somewhere around 500 Longworth chucks cut at this point and the last 300+ have been with the 1/4" Whiteside compression bit. When I started cutting chucks it took about 16 minutes to cut one 16" disc but with this bit and cutting in one pass I cut the entire set in about 8 minutes.

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difalkner

· #8 · Dec 8, 2021

Afish said:
@difalkner are you cutting conventional or climb?

My typical approach is to climb cut full depth with tabs and leave about 0.007" on the side wall, then make a final smoothing pass in conventional to clean up the last 0.007" and remove the tabs. That way I have virtually no sanding to do when the chucks come off the machine. I also do this with other projects where I come back with a final pass to clean the edge. Some projects require that I leave the tabs, some don't.

Cncest

· #9 · Dec 10, 2021

I use these to remove the fuzz. Use in a drill press or a hand drill. The results are excellent.

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Afish

Discussion Starter · #10 · Dec 10, 2021

3

Rectangle House Font Art Facade

Wood Font Art Hardwood Rectangle

rendering

Rectangle House Font Art Facade

Final

Wood Font Art Hardwood Rectangle

This is the personalized ones I did for the kids. They both liked having their full name, personally I think I liked the one letter better. However they both agreed "for once" so I wasnt about to question that.

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Afish

Discussion Starter · #11 · Dec 10, 2021

I did also add some 2" casters not pictured. for easy transporting to and from laundry room.

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difalkner

· #12 · Dec 10, 2021

That's a great project! Looks like it came out nicely. Good job!

TimPa

· #13 · Dec 10, 2021

you have some interesting joinery going on there! did you do those on the cnc as well?

i see what you are saying - that is a lot of cuts to be "fuzz sanding"...

4DThinker

· #14 · Dec 10, 2021

For best results I use a 3/16" downcut bit for the first layer, then switch to a 3/16" upcut bit for the last few.
Love your project BTW. Great excuse for a CNC and some CNC joinery.
4D

Reactions: 1

Afish

Discussion Starter · #15 · Dec 10, 2021

2

The joints where made with the Aspire box gadget and the tenon you see is a 5mm festool domino. The domino locks the finger joint together so you physically have to tear the domino through the wood to separate it. Its probably overkill but I knew if I didnt do it my kids would be testing the glue for sure. This way they should be the last basket/hamper I ever need.

The entire thing started because I wanted to add a vacuum press to the shop that can do 4x8 sheets. But I have very limited room so I need to make it a flip up design in order to have some elbow room when not in use. That also meant maximizing storage space in the laundry area and building a new cabinet to house them. We needed new baskets anyways but they all a taper in them which wastes space and I was worried that if I built a cabinet just for the baskets and needed new ones later I might not be able to find the same ones. So this brings me to building laundry baskets.... Here is a fast rendering of the flip up vacuum press. the large cabinet on the far end is big enough to hold all 4 full size rolling baskets and 4 additional half height ones for misc. items like rags, car micro fibers, etc.

Rectangle Parallel Font Electric blue Facade

Rectangle Font Parallel Slope House

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