Does this look like a CNC Machine ???? - Page 6

# Thread: Does this look like a CNC Machine ????

1. Is this an up-cut or down-cut bit? What is under your plywood part? Is this a 2 flute bit? Depth of cut? If you are trying to take more than 1 diameter in depth you should slow it down...

2. flyrc,

Running 30 ipm at 2000 rpm = .0038 chip load on a 4 flute or .0075 on a 2 flute. That's heavy even for a 1/2" cutter.

You want to run about .0005 or .001 chip load on something that small (I'm being very conservative, calculating for harder material, substitute numbers that work for wood). To calculate the feed rate, use the knowns CL = Chip Load, RPM = Max RPM for cutter, FL = Number of flutes. Calculate the max RPM you can (safely) run your machine. (I generally run mine at 95% of max RPM)

CL x RPM X FL = IPM
or
.0005 x 2000 x 4 = 4 IPM :sleep:

To calculate the chip load for what you're running;

IPM ÷ RPM ÷ FL = CL
or
30 ÷ 2000 ÷ 4 = .0038

Keep in mind that the ply will have glue in it, which may be clogging your cutter as well, shortening it's life.

HTH

Rekd teh Inebriated

3. lsfoils

Is this an up-cut or down-cut bit?
not sure that his means...
but I was cutting from 0 to + Y when it happen

What is under your plywood part?
I have nothing under the part, ( at best it leaves a hair line
it hits the bottom )

Is this a 2 flute bit? Depth of cut?
Yes its 2 flute, ( I was cutting 1/8 light ply)

If you are trying to take more than 1 diameter in depth you should slow it down...
( probably have to do it in two passes)

Thanks,

4. Flyrc I am going to make you a deal, you buy a \$10 cutter from Japan, Germany or the USA and if it breaks cutting 1/8" lite ply at 30ipm/20000rpm I will send you the \$10 via paypal.

Make sure it is not cutting harder substances under it though.

Ken Shea

Keep me posted, it will be worth \$10 to know.

PS
i am talking initial cuts not 6 months from now

5. will due !

I tryed to place my order.. but ther site does not seem to be working.. ( getting all kinds of db errors )

from www.precisecut.com that is..

So Close Yet so Far way...

( I have all my Drawing done.. just need took cut it all out.. ( the rest will be balsa.. 3/32 and 1/8 ) I dont expect it to fail then because I was cutting test pieces out of that..

to be on the safe side I will probably cut it in 2 passes.(for ply that is, so I can get my parts done.. )

Thanks for the support guys..

Rekd,

thanks for the formulas.. ( I will apply them and report back results when I have bits.. )

6. Some bits eject the chip out of the top of the cut some eject them out of the bottom. Its the spiral of the bit at work here. Down cutting bits are handy for through cuts when the chips have some place to go. Like when the part is suspended. But they will clog up and break when there is no place for them to go. To check which you have: slowly turn the bit with one hand in a counterclockwise direction, viewed from the cutting end. Allow your finger nail to ride along the edge of the flute. If it rides toward the shank of the bit its an up-cut bit. If your finger nail rides toward the cutting end then its a down-cut. Hope this helps.

7. If your bit is real long, you need to slow down, as it will break more easily. I used a 1/16" bit that has 1/4" flutes. I think I was cutting lite ply at around 20". Another problem is when the ply lifts up, and starts riding on the non fluted part of the bit. BTW get carbide endmills for plywood. Lasts longer.

Eric

8. Well I'm cuttin again,

Found a Carbite Bit at the local Ace Hardware ( Dremel make it)
It looks like what they call a "Chip Breaker" at least on some of the site that sell the tools,

Its Dremel Part 569,

9. Well for now I slowed it down, to 15IPM and started with a feed over ride at 75% and was playing with it .. (I cut a few balsa parts at.. 40IPM and it seem to do fine.. ( but slowed it back down before I break it..I will run it slow atleast till I finish my first plane )

10. Very nice work, what plane is it?

11. You rule. Looks great. Nice job. I can wait to cut a part again.

Eric

12. Paul,

Here is the finished Plane...

this is a 1/2a scratch build model, I'm just making it REALY BIG NOW, at 32" for the fuse and 37 " wing...

I can hear the guys at the filed now....

Some how I have been know for having samll planes,

I have a speedy bee, a new bee, a Kadet Senorita, a SCAT KAT, AroStar 40 wich got wrecked, a U2 Free Flight wich I converted to RC, a P47 1/2a.. and before I started buildign my cnc I had a Gipsy Month 1/2a in the works, and also a scratch build Auto Gyro.....(I'm sure I will finishe them later )

but the pic below shows what the plane should look like when finished... ( structuraly it will be much diff...but the basic lines will be the same)

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