Gallery, Projects and General > How do I??
How do I cut some rings?
John Hill:
OK, thanks to all. John Bogs, I made a cutting tool just like that but I had a lot of trouble with chatter even on the slowest speed though increasing the feed pressure did get the chatter (almost) under control.
No, I dont have a mill though I may have a shaper if I 'win' the auction tonight.
I will be reading through the other ideas again before making another attempt! Thanks to all.
sbwhart:
John
I'm making some hubs on my elbow thread that a similar in size to what your after, this may help.
Cheers
Stew
John Hill:
OK, I got some progress, I got a ring cut after bolting the plate to a face plate, using a bit of board between. The board was probably a mistake as it was not true and I was too stupid to true it up! It was bolted at the corners and in the centre.
The trepanning went well when I got the tool the right shape and the right feed and speed, metal came off in long blue streamers, very pretty.
Now I have been making the hub for my gyro wheel, two pieces with a thread between. It seems that nothing is ever true once taken out of the 3 jaw and put back in! Is that normal? Even when I centre drill the work before taking out and use the tail stock to centre it when putting it back it is ever only close.
Yes, I know :worthless: but the camera is not here right now. :beer:
sbwhart:
John
It depends what you mean by true ?, a good chuck will only repeat to a couple of 0.001" you'll find that it will perform better using one position to tighten up on experiment to find the best.
If you want better that this you'll have to change your holding technique, collets, or even working of a bespocke mandrell turned up and kept in the chuck so that you can load and unload the work from it, or work from a four jaw and clock the work up each time you load it.
One problem you may be finding with the discs is that its not going in flat you may have to put a stop behind it in the chuck to push up against to ensure its flat.
Hope this helps
Stew
bogstandard:
John,
Stew has hit the nail on the head.
Accuracy always comes at a price. That is a fact of life. Either you have to spend time setting up with a four jaw independant, waste materials to make holding mandrels, that can only be used the once, because when they are taken out of the chuck, they will have to be recut, as they lose all concentricity as soon as you slacken off the chuck jaws. Or you purchase items that will allow you to get the repeatable accuracy that you require.
I am the type who will spend cash to get it, I am not boasting or gloating about it, It is just that I class my time as more precious than cash, and I need it to carry out the jobs I do for monetary exchange. But don't get me wrong, I am not silly about it, if I can get something cheaper to do the job, I will do, I don't go for the most expensive bits, like some people do. But at times, quality does make a huge difference. The cost of machine tooling for say a new lathe, will cost between about 50% to over 100% of the cost of the original machine. Again hard facts of life.
Not everyone has that facility, again, a fact of life, and doing it on a shoestring is nothing to be ashamed of, family and personal needs must always come first. So in that situation, you usually have to do it the long and hard way.
I have found and always said, that the cheapest way to get spot on accuracy for circular parts using a 3 jaw is to invest in a set of soft jaws for your chuck. Mine cost me about 20 to 30 squid a set, and I have them for every self centring chuck I own. If they are used intelligently, they will easily last the life of a chuck (again, I will replace my most used chucks every few years, they do wear over time).
If I get the time over the next few weeks, I will do a bit of a write up to show you how to easily improve your accuracy, either with standard practices, or spending a little cash, to make it a permanent thing.
John
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version