Burned holes in solid wood

[lunaj76]

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]

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

[Kenrbass]

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]

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

[lunaj76]

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]

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]

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]

I do not see a video.

[Regnar]

lets see if it shows up this time.

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

[lunaj76]

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

[Regnar]

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.

[Travish]

Good find Russell,

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

[Regnar]

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.