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I've got a project coming up where I'll be making a dozen peppermills, using crushgrind mechanism. My Frued forstner bits overheated and generally were a disappointment. So the question, for those who do mills, what is best drilling solution for lathe drillin?
demps
I always used Bormax, with extensions as necessary. Pricey, but they held up to the task.
Bill,Quote:
Originally Posted by Bill Dempsey
I always use relatively cheap carbide Forstner bit for drilling pepper mills since they last forever. The high quality steel bits will leave a smoother hole but that's not very important for the inside of pepper grinders. I don't know the brand of my set, unlabeled and bought on sale from Woodcraft 20 years ago. However, I recently bought a few inexpensive sets of metric carbide bits from Amazon and they seem to work as well.
On tip: for most drilling on the lathe with Forstner bits I don't use a Jacob's chuck. I mount the bits in a #2MT end mill holder that fits directly into the tailstock quill.
https://www.amazon.com/gp/product/B01MXSP25W
This requires bits with round rather than hex shafts (mine are 3/8"). Pepper mills may require an extension. For deep, large diameter holes I keep the end mill holder from turning with pliers or vise grips (a Jacob's chuck often needs to be kept from spinning in the tailstock by gripping firmly with the hand.)
As for heat: I devised a method to drill deep holes and minimize overheating with any kind of Forstner bit. While drilling I direct a continuous stream of compressed air into the open end of the hole. This not only cools the bit but clears out all the chips (which also helps keep the bit cool.) This method also usually lets me drill the entire hole much quicker since I don't have to stop and back out the bit to clear the chips. Perhaps lots of people use this method but if so I haven't run into any of them yet and I've been preaching it for a dozen years.
JKJ
Nothing beats the Woodcut Mill Drill for the Crushgrind Mechanism. Here is a quick video of how it works. https://www.youtube.com/watch?v=ZB83sykMLaw I also did a review of it in More Woodturning Magazine.
Nice idea, I haven't seen that one. Might be worth buying for some who made a lot of pepper mills. Looks like it wouldn't be hard to make one (for a metalworker). I like the Morse taper mount too.Quote:
Originally Posted by Bill Blasic
JKJ
Search Google for "boring bar for metal lathe". I drilled a 1" hole through the blank, then I opened up the bottom of the blank with a homemade boring bar jig. Reversed the blank mounted on a 1" expanding mandrel shaft to keep it aligned and drilled out the top hole.
Often, excessive heat while drilling is caused by a dull drill bit. Basically the combination of the friction, rotational speed and pressure are being converted to heat. Drilling slower will help to some extent. Lubricating the bit will help, and having a sharp bit will help.
Google "captain eddie castelin sharpening forstner bit". He shows how very very simple it is to sharpen them.
Sometimes when I'm drilling with a forstner, I will periodically squirt in some WD40. It doesn't seem to affect finishing. I suspect that mineral oil or BLO or a variety of other oil/wax/lubricants would work. John K Jordan's suggestion of blowing in compressed air is also a very good idea. I recently built a vacuum chuck adapter for my lathe. It seems a shame to not have a use for the exhaust air - - So, I'm going to follow John's suggestion and rig it up for also blowing air along my forstner bit.
I've been using the Colt Maxicut bits with the RotaStop system for many years with good success. They're high speed steel and hold up well. The problem with drilling out pepper mills is you are drilling directly into endgrain which is tough on any bit. Many good suggestions above as well. Good luck and show us what you end up with for mills.
I also use the Colt Maxicut. It plugs straight into the Morse taper socket on the tailstock quill for best alignment and maximizes use of space on a mini lathe. It is the fastest and coolest cutting Forstner bit that I have ever used. Because they cut so cleanly they don't get hot. Because of the unique design they are easy to sharpen with a diamond card.Quote:
Originally Posted by Don Orr