Plywood chip out

[phd1658]

Hi all,

My Son is working on a project for his boss which involves v carving a pattern on plywood. He is using 3/4" with oak veneer, utilizing a follow the vectors strategy- .1" deep with a 30 degree 1/4 Vbit. His feed speed is 3 in/sec and rpm on the router is 16K. His thought was that he could use colored resin to fill in the grooves.

The problem is that the veneer is chipping/tearing in a couple of places along the cut line(s). I did a cursory search on the forum, but couldn't find any answers. I'm not sure what to tell him, slow the feed down, make two .05 passes, speed up the rpm, cover the cut areas with mask?

If someone could point him in the right direction, I would appreciate it.

Thanks,

Bill

[bleeth]

Bill: The feed is OK but he could probably spin it a lot slower (10-12k) considering the shallow depth. If he is getting tearout that is more than minimal then there could be a couple of causes. First is the bit quality and/or sharpness. Second is the plywood itself. Many of the imports will have more issue than domestic or Canadian plywood.

[Gary Campbell]

Bill...
Those speeds seem appropriate.

In a lot of cases, all but the highest quality (read as most expensive) plywood will do this as a result of lesser quality core plys. These same plwood brands dont use the best glues, and they apply it sparsly. Most brands at the big box stores fall in this category.

Columbia PureBond does not. It has good domestic core plys and is very consistant from sheet to sheet. I heard that you can get it at the BORG.

[phd1658]

Thanks, guys. Brand new bit, so it's probably the plywood. He bought it at one of the big box stores. The bottom side of the piece will never be seen, so I suggested he keep playing with the side he's on until he works out all his parameters. Will suggest slowing the rpms.

[wberminio]

Definitely a plywood core issue,especially on oak veneer.
Bits need to be sharp.

[fozzyber]

Try laying tape or mask on top then cut. This helps some times

[phd1658]

Thanks, all. Will try slowing the rpms and using masking tape. Like I said, the bottom will not be seen, so he can keep experiementing with the side he started on, then flip it if he finds a winning combination. From reading the comments I'm pretty well satisfied that it is the quality of the plywood. Fortunately, the piece is only 2x4 feet, so if nothing else works, I believe the big box has edge glued wood pieces that size. Meantime, I'll also look at sourcing some better plywood!

[knight_toolworks]

keep the rpms up it will help but slow the cut down to about 1ips. I do this on tearout prone woods. the 60 bit tends to tear more anyway.

[bob_reda]

If worst comes to worst use a 1/8" downcut spiral bit for the grooves, should give a cleaner cut and a little more area for the epoxy filler to frab

Bob

[jimboy]

Bill,
I had a similar problem on plywood and found a solution by accident. When I sprayed the surface with poly and then v-carved the tear out was almost non-existent. I don’t know if that is possible in your sons case but thought I would pass the info on.
Jim

[jimboy]

Addition info on poly . After I finished I just sanded the poly off the surface.
Jim