Questions about machining Birch Ply and Apple Ply

[widgetworks_unlimited]

I've been working on a couple of new products and been having issues cutting 3/4" birch ply.

I've cut it many times before for jigs and didn't notice problems, but now that I'm trying to tweak production files I'm finding that birch is a lot tougher (denser) to cut than the poplar or pine core plywood that I usual use. My PC router is bogging down when I cut and dropping my feed rates leaves my bit burning hot. (I know... a spindle wouldn't have this problem. But, that's not in the cards at the moment.)

Ermino mentioned Apply Ply as an possible alternative to the birch, but neither of us have much experience with it.

Anyone cutting apple ply or some other thin layer/voidless core material that isn't as tough as birch?

[Brady Watson]

Russ,
If you are trying to cut in a single pass with a compression spiral, I can see where you are having issues with the router.

You may want to try my Poor Man's Compression Bit (http://www.shopbotblog.com/index.php/2007/03/a-tale-of-three-bits%E2%80%A6and-the-poor-man%E2%80%99s-compression-spiral-trick/), using a downcut to cut 1/4" deep, then swap out to an upcut to finish out the rest.

It gives you nice clean top & bottom faces & your router shouldn't bog down.

-B

[dlcw]

For your first toolpath, using a compression mortise bit, cut in a climb direction taking 1/4" cuts with each pass. Your initial plunge of 1/4" will put the downcut spiral part of the bit just below the top of the veneer making for a clean cut. Have this tool path cut all the way through in 1/4" passes leaving a 1/64" skin. Now create a second toolpath that will cut conventional. Set the toolpath so it goes about 1/64" through the material. This will utilize the up-spiral part of the MC bit to create a cleancut on the bottom veneer. You can put all of these toolpaths into one file.

I use this exact process every time I cut any type of plywood (except I take a 3/8" pass instead of 1/4" pass because I have a spindle). The part dimensions are exact when done and both top and bottom veneers are a super clean and crisp cut with no chipping at all. It doesn't matter the type or species of plywood or even if it's melamine.

It takes a little more CNC time, but I can reduce the wear and tear on my spindle and get perfect results every time.

[knight_toolworks]

I use a smaller bit so the sawdust holds parts in place. so I would use a 5/32 downcut bit cut two passes almost through with a climb cut and a final pass clockwise full depth. I can cut it at 3ips but not sure if you can cut that fast.
if your spoilboard is not to hacked up you can get a clean cut on the down face. you can do the same thing with a 1/4" but if the pieces will stay in place.

[widgetworks_unlimited]

I'm still curios to find out what "Apply Ply" is really made of and how it cuts compared to birch. Anyone with experience???


I suppose I should have listed more details on my current cut strategy with the birch...

I'm using the techniques described by Brady/Don - these have always worked well with other MDF and poplar/pine core maple veneer plywood.

For the birch I've settled on 3/8 diameter down spiral @ 4.5 ips, cutting 2x climb cut passes @ approx 3/8" deep each, leaving a .050 onion skin. I run a second finishing cut with a 3/8" diameter mortise compression spiral, conventional cut @ 6 ips, cutting 0.050" into the spoil board.

With other plywoods and MDF I usually rough cut at 5 ips / 3/8" deep per pass. (I had been cutting these at 6 ips successfully, but found it caused too much arcing/wear on the armature of the router, so I reduced my feed rate to 5 ips and everything has been great until now.) I've tried cutting the birch even slower at 4 ips and I've also tried 1/4" deep per pass. These changes leave the cutter even hotter (I'm assuming due to the reduced chip load) and don't seem to help much with torque.

I've got a new bit coming to test, and I've changed my vacuum setup to reduce power consumption during the roughing cut - it appears that Edison is being stingy with the power and that my new vacuum setup is pushing me to their limit, even though I'm well below what the shop is wired for.

I didn't want to open up the router and check the brushes, (replaced recently, along with the bearings) but that may be the next thing to rule out.

Steve's advice to back down to a smaller cutter may be the winner.

Who knows how long this torture routine will go on!

[knight_toolworks]

I have been playing with smaller bits for awhile. I can really cut more out of a sheet because of it. but say you want to cut with a 1/4" bit in 3/4" material you would have to cut it in one pass and maybe a cleanup pass.
but I did find cutting bamboo only 1/2" thick I could not get a clean cut with the 5/32 bit.

[oddcoach]

apple ply is made on the west coast and machines very nicely, of course it is expensive.
A lot of suppliers are using Chinese multiply, it machines like pooh no matter what you do and is murder on tooling. It sounds like this is what you have. it also warps like crazy. talk to the supplier if you cannot get Apple ply try for Baltic birch or anything from Europe. all of the multi plys are little tougher o cut than normal cabinet plywood because of the extra glue
hope this helps
John

[woodworx]

Appleply is from States industries in Eugene, OR. It is an alder core. The nice multiply panels are much more stable than a Chinese import. The core gaps and overlapping of the inner plys is what causes a potato chip plywood. Baltic birch and Appleply uses a nearly void free core and uses much more stable material to make up the core. The Chinese LLLOOOOVVVEEEE glue! It will hold anything together long enough to get back to your shop, and then you notice that it is an inferior sheet. The glue is hard on your bits, and will cause them to dull much faster.

[dlcw]

I've cut in to Chinese plywood and found metal and rubber in the lamination's. Ruined a really nice 80-tooth veneer tablesaw blade. Not allowed in my shop anymore.

[kevin]

It's invading Canada too. GARBAGE!

What's nice about North American plywood, especially Columbian, I think it is almost water based glue. God knows what is in Chinese. Water based glue is a huge selling feature. Customers would prefer having their fruit sitting inside water based glue cabinets. They are starting to bring in a lot of chinese cabinets in our area. People here think it is garbage. But I was surprised with the shop bot. I made cabinets for a discount furniture store using MDF doors and we were actually able to compete. I don't want to get anti-chinese here but in a lot of places are crippled and as cabinet makers we should only buy North american. It is getting ridiculous at the price point. People are always looking for cheap cheap cheap. There is no furniture manufacturing left. I won't put chinese plywood on my shop bot.