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-   -   Burned holes in solid wood (http://www.mechmate.com/forums/showthread.php?t=3060)

lunaj76 Mon 27 September 2010 18:22

Burned holes in solid wood
 
Hello,

Here is my problem, I want to use a compression bit to machine a part in solid wood that has pockets, dados and holes. I don't want to do a tool change to drill the holes .5" I have tried using a .5" spiral upcut and can cut the holes very well but the compression bit I can't get not to burn. I like using the compression bit to machine everything else on the part because it leaves a great surface finish.

Does anyone have any other bit suggestions or feedback?

Thanks

Justin

Kobus_Joubert Mon 27 September 2010 23:00

Try to blow into the hole with compressed air to get rid of it ASAP before it burns

Kenrbass Tue 28 September 2010 07:29

If you set it for "peck drilling" it will help a lot. Depending on your program and if you have that option. Have it plunge a little at a time and come out for cooliing. The section where the up and down spiral meets is the spot that has a hard time ejecting the chips.

Sometimes it is just best to go back to a straight bit for those cuts.

I get burn spots hole drilling in plywood too. Mortise comp. bits tend to be a little worse than regular comp. bits depending on brand.

If you can step down to a 3/8 bit and let the cut be a pocket instead of a straight plunge, your burning will stop. Set if for a spiral cut on the pocket and there will be some room for the chips to escape.

Ken

Travish Tue 28 September 2010 14:02

Ken's got it right, Helical bore it or spiral down the hole. Very effective.

lunaj76 Tue 28 September 2010 21:31

Thanks guys for your suggestions!

I think the best bet for me will be to just use a upcut spiral instead of a compression spiral. I have tried air and peck drill they did help. Drilling a hole gives me a better cut than a pocket. I think my 35 tooth pinions combined with a little bit of backlash in my 7.2 gears are not giving the best results with small circle pocket cuts. But that's another story.

P.S. How do you guys do a helical bore?

Justin

KenC Wed 29 September 2010 08:16

My expereince with cutting small holes by setting spiral down cut is that the hole dimension are not accurate enough. no doubt that it stop the burning.

Regnar Wed 29 September 2010 17:32

Justin a Helical Bore is just a inside profile cut of a circle that is constantly ramping down.

If you use vcarve you will find this option in the ramping area. I love this feature over the plunging and cutting and usually your cutting speeds are faster.

Here is a video showing the Helical Boring. It is around minute 2:30 of the video.

domino11 Wed 29 September 2010 17:44

I do not see a video. :rolleyes:

Regnar Wed 29 September 2010 18:39

lets see if it shows up this time. :o

http://www.youtube.com/watch?v=om6GQKfoS1g

lunaj76 Wed 29 September 2010 20:58

Thanks for the lesson in vcarve I will give it a try.

Regnar Thu 30 September 2010 17:57

Just be sure to increase your plunge rate. I go as fast as the cutting speed most of the time. You will have to play around with it a little. Most people I tell about this hidden feature usually love it. Although the first time doing it is kinda scary whatching it plunge in a 300ipm. :eek:

Travish Thu 07 October 2010 14:32

Good find Russell,

That gives a good example there. Play with your ramp angles too. This can vary widely as well.

Regnar Fri 08 October 2010 07:08

Travis, The ramp angle is determined by your cutting depth and length of the vector. I dont have Vcarve loaded on this computer and cant get to it for another week but I want to say your looking for what is called "Spiral" in the ramping section.


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