Baltic Birch Drilling Problems

[McBuster]

A Final Update !

I ran a test of drilling holes thru the ply without any backer material. The attached image shows how these little discs from an End Mill get in the way ...

Searching for a Drill(ing) type bit ...

Jon ...
Woodbury Mn
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[norseman]

Maybe this:
http://tinyurl.com/pxwa2ro

[Eagle55]

Been following this thread for the learning experience. The "drilling mill" in the previous post would likely solve that final problem. Also made me think of a tool that you might already have in your rack. The round nose bit. It would slowly plunge through the bottom of the material without creating the "disk" at the bottom of the hole. Backing plate would make cleaner holes but not sure how much that matters. Not that this would be the final solution or anything but just an idea and like I say may be something that you have on your tool rack. I like drilling with a mill but one reason is for the flat bottom. I rarely drill all the way through so haven't experience this problem, but have in the past when using forstner bits in the drill press.

Roger

[McBuster]

Thanks for link to a Boring bit ... Will explore that tomorrow.

Jon ...
Woodbury Mn

[McBuster]

Tried an experiment. Use the 90 degree bit to put a chamfer on the edge of the hole. Top and bottom. The drill the hole. That means, tolerances are almost non-existent. And the piece as to be symmetrical side to side, or top to bottom. When I do the production pieces, the top surface will have a chamfer so this works out okay.

Some pix ... All was done without the aid of jigs to register or hold in place.

1) Drilling the holes after C'Sink both sides.
2) Back side - off a little.
3) Front - real good.

Next time I will not trace the hole diameter with the V-Bit. The point then may leave flat spots. But, trace a smaller diameter and plunge the bit lower so the hole drill hits the sides of the chamfer. Not the face of where the V traced.
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[rungemach]

You may want to try this for getting a good cut through ply that has tear out issues. I use a smaller bit than the hole diameter, use an inside profile cut, ramp the cut so it does not plunge straight in, set the tool plunge speed at the same value as the feed value, (like 10 for both), ramp length equals the circumference of the hole or a little smaller, and do the first pass so that it does not fully penetrate the top layer of ply.

What this gives you is a smooth spiraling cut to get you through the top later of ply in two passes. after that you can do a second tool path that gets more aggressive with the feed rate as you have already cut through the layer of material prone to tearing. You did something similar when you made your v bit pass to establish a clean hole through the top layer. This way you do not need to change bits.

I do this with complex shapes to get good tear out free top surfaces and it works pretty well. if you try and plunge or drill though the first ply later to aggressively, you can easily get tear out issues.

If you have an HD machine , it should not have rock or "free play" in it. I believe it is supposed to have adjustable bearings to be able to grip the x or y bearing rods without slop in the bearings. It may have some flex and springbuck when you put force on the router bit, but should not have any loose free play. Some sharks arrive with loose bolts in various places, so it may be worthwhile for you to check and tighten everything.

If your router is loose in the clamp, try the sandpaper fix or consider the large aluminum clamp the Sam at Dixie Billet makes.

[McBuster]

Rungemach

I do not have issues with penetrating the ply. I have issues at the bottom when the bit gets thru the ply. For cosmetic reasons, I can not have any breakouts.

All nuts and bolts tightened, see my other post. The Y Axis was a disappointment. Yes, I have an HD 2.0 plus the aluminum clamp Sam sells.

Now, I am thinking of boring two 1/8" holes in two corners on top, or the bottom. Then, use pins to register each piece no matter if working on the top or bottom. The top surface holes need to be chamfered, the bottom does not. I will try this approach later today to see how the tolerances stack up.

And of course, how much effort in time does it take to make a single usable piece. What I have offered here, is the replacement for the extruded bed. When up to speed, the production units will have two pieces of ply about 9" square and have one hundred holes in each. All must line up. All holes must be pristine.

All ...

Thanks for all the ideas and concern. My first exposure to a desktop Cnc Thingy.

Jon ...
Woodbury Mn

[McBuster]

Problem Resolved!

Here is the bit to use for boring holes in wood.

http://www.freudtools.com/p-172-mortise ... piral.aspx

Just finished doing about 2000 1/2" holes and absolutely clean entry and exit. No backer board required.

The end of this honker is Pure Mean!

I will not be adding anything more to this thread, except responding to others.

Thanks every one for helping!!!

Jon ...
Woodbury Mn