So I’ve got a project where I’m building some mini cornhole boards (1’x2’ instead of 2’x4’, look it up it’s a thing 
) anyway I’m using a plywood which has a veneer and is prefinished for the parts and it looks great, but when I drill the holes for the parts to be screwed together (pivoting legs) the back side is blowing out pretty horifically, I can’t figure out what to do to make sure it stays intact, I’m using a 1/4" Compression bit to go through the material any thoughts on how folks are doing this? That same bit is having no problem cutting clean edges on the same material when it cuts things out.
You can’t use a compression/upcut/downcut anything to DRILL holes. You are ok with BORING holes.
Boring means the hole is larger than the bit that does the boring - it goes in circles as it goes down.
I am actually surprised that you didn’t complain about the holes being all burned - that is the normal result when you try to force a bit to do a drilling operation when it’s not designed to drill.
Use a bit that is designed to drill! Use peck drilling if the depth is larger than about the diameter of the hole.
Just to add - make sure you don’t try to drill into thin air below the hole (such as T-slot rails) - always have material there that supports the material being cut.
Most veneered plywood has veneer that is less than a hair thick. The veneer will peel if you look at it funny 
Normal cutting sheers the veneer sideways and there is a lot of bonded area between the veneer and the plywood. A drilling operation pushes the veneer straight down and, if not supported, will look like crap.
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Okay that kind of makes sense but is slight unintuitive as I’d thing something that cuts down into the wood would be capable of just doing to its own depth. I guess I should find a good source of 1/4” shank bits for drilling in various diameters?
Now that is funny lol. Sounds like a lesson learned =)
Yes, lesson learned … but not with the mill
Not sure what ‘would be capable to it’s own depth’ means.
What size hole are you trying to drill? You can do a lot with a 1/8 endmill. If the hole is maybe 3/16 or larger, I would bore it. Note that sometimes (for larger holes) you might have to do two passes so that you don’t end up with the boring operation generating a slug which might go flying.
Another option - I use PCB drill bits with 1/8" shank. They are very inexpensive and there are all kinds of sizes available. I would NOT use a 1/4" shank bit to drill small holes - they are way too expensive because of the heavy shank. Also, smaller bits are fragile and it’s much easier on the pocket book if you loose a $2 bit vs a $20 bit (and you will loose some).
You can have the mill drill a small pilot hole and follow that up with a hand drill or drill press. The pilot hole makes sure you are located accurately. Be sure to have backing on the hole!
PCB drill bits are easy to find to 1.2 mm but can go to as much as 3 mm. Buy in sets of 10 and you are probably looking at $1.50 CAD or so a piece.
Remember … peck drilling!
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Like Jens said, if you want to drill you need a drill bit. There are few on the market. Jenny makes molly bits in 1/4 and 1/8 that you can use for drilling and few other things like chamfer etc. IDC woodcraft sells 1/4 and 1/8 drill bits. If you want to use compression bit you need to do bore operation
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@gremlin You have not mentioned what CAD/CAM application you are using. In addition to the advice that you have already received, I will add that, in VCarve, a very accurate and non-destructive way to bore holes is to use an end mill smaller than the hole diameter, and cut a profile toolpath inside the line, using a spiral ramp. You will still need to support the bottom of the material - as you do with a drill press - but the hole will be clean and the veneer will not be torn out.
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I use VCarve Pro so I’ll give that a shot, sonuds like a good way to do this is to use a downcut bit and have it got most of the way in with a spiraling path and then follow up with a drill press or a hand-held through the rest of the way with a backing board.
When I said would be capable of it’s own depth, I mis-typed, I was talking about a drill bit that could have a 1/4" shaft and be the correct diameter. Reading more it seems like it’s really not a thing to use a drill bit in a cnc like this, as most folks are worried about the RPM on the spindle etc.