Drilling mirror chamber for kaleidoscope

[Thor Sorensen]

I am new to turning and am planning on making kaleidoscopes that are 8 to 10" long. How would you drill a 1-5/8" hole in though the center(end grain) of a glued up block for the mirror? I have a General mini lathe with a slowest speed around 450 rpm, and a Jet 17" drill press. It seems that it would be better to do it on the lathe if I can.

What type of bit would you use?

I did a search and find mention of kaleidoscope designs that are glued up from 3 peices so the center is open and avoids the drilling. However I want to use a single block on some of them without the glue up lines.

I have been lurking for a while and learned a lot from you already - thanks.

[Paul Engle]

Thor, I use a Fostner on either the lathe or drill press for my candle sticks, confetti lites,other drilling needs, extensions are avail at the tool stores to get the reach.450 plenty slow, may burn somewhat if you plunge too slow , but you could clean that up with parting tool or 1/2 inch skew taking light cut/s

[Andy Hoyt]

Were it me, I'd do this on the lathe with good old fashioned twist bits. Start at maybe 3/4", then 1 3/8", and finish at 1 5/8". And I'd do so at a very low speed - perhaps 100 to 150 rpms.

I've found forstner bits to be too slow at cutting end grain and heat up far too fast.

On the other hand that 1 5/8" twist bit may well be tough to find - and pricey if/when you do.

[Curt Fuller]

If you turn the piece round first, turning a tenon on both ends and mark your centers as exact as possible you can hold it with a scroll chuck and put a forstner bit in a drill chuck in the tailstock. Drill it half way and then turn it around and drill the other half from the other end. The hole may not be aligned perfectly but close enough to mount the mirrors. That's how I've drilled peppermills and they are within 1/16" usually.

[Thor Sorensen]

Thanks for the advice. You have confirmed some of my fears about the forsterner bit and speed of the lathe. My slowest speed is 450 rpm.

Do you think the sprial bit will produce less heat? Can I run it that fast?

[Greg Savage]

Try a BorMax bit.....It is basically a forstner on steroids. I use these on my peppermills and they are great. There is an extention for them also.

http://www.woodcraft.com/family.aspx?FamilyID=1917

[Andy Hoyt]

Only one way to find out!

Hey - 'bout time you spoke up in here. Lurking for a whole year - tsk tsk :D

Welcome!

EDIT: Nice find, Greg. That might just be the answer. At least I got the pricey part right.

[Thor Sorensen]

Thanks Andy and Greg. I will try and pick up a Bormax bit and see how it works. Hopefully the local Woodcraft has it in stock.

[Robert E Lee]

How about doing it like a inside out xmas ornament. It might take a little practice to get the right size but would be a little cheaper.
Bob

[Frank Fusco]

Try a BorMax bit.....It is basically a forstner on steroids. I use these on my peppermills and they are great. There is an extention for them also.

http://www.woodcraft.com/family.aspx?FamilyID=1917

That is an interesting tip. Like others, I would not reccomend the Forstner for your k'scope because of burning. The Forstner (style) is designed for cross-grain boring. I do a lot of 3/4" end grain boring and have settled on a brad point. But, I might try the BorMax, never heard of them. Costly buggers though. For the big bore, I hope you intend to sell several of your k'scopes to recover cost.

[Greg Savage]

I'm glad that I could provide some useful info. These bits have razor-like teeth and at slow speed, they cut beautifully. They may be a pain to sharpen if necessary. I have made pep-mills with Bubinga and also Koa and there were no burn marks. The extention is precisely machined so drilling an accurate hole is still possible. However, BorMax bits do take a bite out of the wallet.

Cheers,
Greg