Sometimes I have to turn small or thin parts in the lathe (a coin or a small pin, for example). There are two common problems with this parts: how to clamp them and how to get repeatibility. If my concern it’s not clear look the parts I need to finish.
Sure, I can clamp one of this parts in the chuck, but I can’t release it and place back in the same position.
There are several alternatives to this issue. I choose what’s is called a chuck spider, something like a support between the chuck and the part. As the part get supported by the spider, you can get off the part, measure, and place back in the same position easily.
Design and Build
Instead of making only one spider and adjust deepth through a spacer, I opt for making three spiders: 2,5mm, 5mm and 7.5mm. Let’s the images tell the history.
To finish the cutting-off side of every spyder, I made an improvised shellac chuck (or “wax chuck”) , a classic watchmaker’s technique (btw, this is also a posible solution to the original problem!). I don’t have shellac wax, so use carnauba wax instead; this works fine for me. Here’s the finished set.
To avoid chuck jaws mark the aluminum surface usually I fold the complete part in strip of aluminum sheet, but this time I wanted to try something different, so I design and made some sort of reusable jaw pads.
What can I say. Every Sherline user should have a spider, they are so great!.
Using the wax chuck was so nice that now I’m thinking on making one with self heating, so you dont have to take off the chuck and put on the stove to put/extract the parts.
I will add some drawings soon for the spider and the pads.
Nice work!!! I was planning to make these myself.
A few questions if you don’t mind:
1) Was that a hot plate you used in “spider_7”?
2) To mill the slots, what is the size of the ball nose endmill you use?
3) Did you go full depth in a single pass? I always encounter problem using the ball nose.
4) You made that indexable chuck holder used in the Sherline vise?
1. Yes, you must heat both, chuck and part, to get wax melt and get a good grip.
2. The ball nose was 1/4″, but may be a smaller radio would be better.
3. You are right, ball nose are problematic. I did most milling with a 5 mm square end mill,
taking 0.5mm per pass (I was confortable with that). For the round finish I don’t remember how much depth per pass, but wasn’t more than 0.5mm in any case.
4. No, this is Sherline product #2045 – Index Block Set.