Hey Guys,, Here is just a short (no chance!) recap on how things transpired on the halfnuts problem on my Maximat Compact 3100. As I had stated, I was having problems with the halfnuts not closing all the way or not at all both when trying to thread ( very annoying) and also when using the leadscrew for feeding. Let me tell you, I just about wore the bolts out on the carriage, taking the halfnuts out to try something somebody had suggested. I appreciated all the help and support from all the people on the Chaski and the EmcoV10 groups who took the time to contribute. I want to extend lots of credit to Paul Fallert whom I got to know on the EmcoV10 site who prodded me to keep looking and offered all kinds of support. He has a Maximat 3100 too. Through one of Paul's friends, Mike Stets, we were finally able to resolve this problem.
Mike writes:
When you attempt to close the halfnuts on the machine when things are in motion,
the nuts do not hunt easilywhich means you must encourage them to engage the screw. At the parting line on each half there should be some clearance milled to relieve the sharp corner of the thread. This relief is around 30 degrees and will allow the nuts to begin to close while picking up the threads on the leadscrew which then allows them to fully engage.
Mike had 35 years experience working at a US Government facility which rebuilt high prescision machine tools. He is host of two videos on machine tools which are currently being offered on Ebay.
Mike goes on to say "Over the years, I have made a few sets of halfnuts and learned that
You need to have this relief to insure smooth operation and engagement. When you rock the hand wheel, you are aligning the the nuts to the screw so they engage. When you exert pressure on the nut lever,
The corners of the nuts are riding on the screw and when the thread is matched up, they engage fully.
When you think about what Mike is saying,,,I makes all the sense in the world!!!!. I whipped them halfnuts out of their hiding place and not having my milling attachment yet,, I used my trusty Dremel tool and proceeded to do what Mike recommends. You could see where the leadscrew had already been trying to do what Mike is talking about. After grinding the relief on all the thread ends, I used a fine file and made sure there were not any rough spots and everything smooth as glass.
IT WORKS,,,IT WORKS!! Man, you just cannot believe how very smooth those halfnuts engage now. I can move the carriage and enage the halfnuts any here on the leadscrew as fast as I can turn the hand wheel.
For the folks that are familiar with the inner workings of a car transmission,,this is the same princciple they use on the synchronizers.
If anybody is interested,, I will take the halfnuts out one more time,,,I can have those babies out and in my hand in a pair of minutes for a pic. OK,, I'm done for this time. Thanks to all. Joe Rivera
