Another question re 1/4" ply

[Donnalu]

I have a job for intricate panels in 1/4" stain-grade material. I was going to use baltic birch for this particular job, but one of the panels is 68" long and baltic birch only comes in 5' x 5' sheets.

Can anyone recommend a good 1/4" ply that machines and stains well?

Many thanks,
Donna

[wberminio]

You can get something called apple ply simpler to Baltic birch-mulitply- but in 4x8 sheets.

[GlenP]

I can get Baltic Birch in 4 x 8 sheets here in canada. I have to order it as not a stock item but it is available. Call some wholesale lumber stores and perhaps they can order some. If not can use just birch plywood. It will look the same stained up.

[knight_toolworks]

what you want to ask for is euro ply or russian ply. little better quality then bb ply and 4x8. apple ply is nice but it is expensive for the most part.

[Donnalu]

Perfect. Thanks so much!

[bleeth]

Another option is mdf core veneer ply. Machines super easy and may be more available than BB or Appleply in the Southeast. May be stockes at your nearest Dixieply.
A couple shops I know who do decorative cutout pattern screen panels as a main item use it.

[Donnalu]

Thanks, Dave! I definately will look into that.

[Donnalu]

Okay, I am using 1/4" mdf core birch--which I really like. Thanks for all of the suggestions! I am having some issues with getting clean cuts, though. I am using a down-cut spiral on the first pass with a .008 offset allowance and up-cut on the second. The problem is that I am getting tear out on the top when I run the second tool path. I am running 75 IPM at 12k. If I remove the offset allowance, I get tool marks on the inside edge. All are conventional cuts. I have tried ramping in and still get these.

Any thoughts?

Thanks,
Donna

[jerry_stanek]

Have you tried a straight bit with a ramp in

[bob_s]

Have you tried running the whole job with the down shear bit. I have found that the bottom side has less tearout because it is in contact with the spoil board. I notice that the ends of your cross shapes are not symmetrical. Did you make them with an arc, the reason I ask is that if they have several segments they will probably tear more as the bit changes velocity and direction, as opposed to running smoothly along an arc or bezier shape. If they are arcs then I think you have a machine that has some extra play somewhere which can also lead to more tear out.
Gary Campbell has several threads here with great instructions on how to get your machine really well aligned and almost error free

[Gary Campbell]

Donna...
Try a 2 flute or even a single flute compression bit and cut in 1 pass. They are available in a 5mm size, which would be my choice for your cutting.

Here is an example: https://www.centuriontools.com/router-bits-toolcase/solid-carbide-wood-router-bits.html?sku=5MMCR21.03RES14&pcn=Compression%20Routers&pid=791&sat=1

[bleeth]

You can also use this one from the same supplier:

https://www.centuriontools.com/router-bits-toolcase/solid-carbide-wood-router-bits.html?sku=14CR21.02.5FEM200&pcn=Compression%20Routers&pid=734&sat=1

The key is to make sure that the lower upcut part is lower overall than the thickness of your material. Don't ramp-Just plunge in and go.

[Donnalu]

Thanks to everyone for your response. This job has me baffled…

Jerry, I ordered some straight bits yesterday, and will give them a try with ramping in; Bob, all of these are straight lines—no arcs. I have attached a screen shot of the nodes. I have tried running the entire job with a downshear, but the back was torn out badly—not a big deal since these will be used for wainscoting, but I would like it to be as clean as possible. I will say, that I think the bit was starting to get dull when I ran the full downshear toolpath.

I will also give the compression bits a go. What baffles me is when I cut the test piece, it came out perfectly--I was elated--no sanding! Then, when I ran the files, they were not nearly as clean as my test piece. I have 15 of these panels to get out by the end of the week. Ugh.

[bob_s]

Donna
I think a very sharp bit will make a difference. I have had a run of MDF for a client lately - hate the stuff, but a very sharpcuts and a dull bit will tear out. There are also many grades of MDF and the good stuff cuts much better than the Big box store variety. The cheaper MDF also seems to have a lot more grit that can dull a bit in 50 feet of cutting while I just cut 1000 feet of shapes in the good stuff and the lucky 1/2" plunge roundover bit was still sharp under a 20 power loupe.
The straight vectors will cause the bit to pause for a split second as it changes direction, and I have had problems with that leaving marks if I am cutting with any speed over about 1.5 ips. The same shape with arcs cut great at 3 or 4 ips.
If your machine is "banging" in those corners I would suggest that you try cutting slower or changing your ramping values to keep it more fluid to lose the marks in the corners.