16th Oct 2009, 09:52 PM #1
Cutting thread and nut on cross slide
Can anybody help or give me some pointers on cutting I think it is an acme thread 7/16 10 tpi ona sheraton lathe cross slide any advice would be gratefull
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17th Oct 2009, 08:03 PM #2Dave J Guest
This tread would have to be the best one I have seen on the internet about cutting a acme thread.
Making a new Cross Slide Acme Screw - Practical Machinist - Largest Manufacturing Technology Forum on the Web
I notice that some small pictures are deleted, so get it copied to your computer before any more go.
Hope it helps you out.
18th Oct 2009, 11:19 AM #3
You may well be able to use a Hercus or Southbend nut for a 9" Sheraton.
If you want to cut a thread in your own nut the hardest part will be making the boring bar. This is how I would do it. Get some silver steel, say 7/16 or a little bigger and turn a diameter that will clear the inside of the thread, leaving a head at the end which will become the cutting edge. Now turn the bit at the end with the right angles etc. for the thread profile, just a 7/16 diameter disk with the faces angled to 7.25 degs each side to match the ACME thread.
Now take it out of the lathe and put it in the vise. File the disk in half and file the back off blending into the root diameter you turned earlier. File some clearance on the inside edge as well as the outside diameter, the front edge won't need clearance due to the course lead of the LH thread. You'll need decent clearance on the inside edge and perhaps some secondary clearance.
Now you need to harden and temper it. I just use a propane torch for this.
18th Oct 2009, 09:54 PM #4
Thanks for your help dave will read through the material i have downloaded and try to make some sense of it
B the B
18th Oct 2009, 10:00 PM #5
Thanks for your help blackfrancis i am only learning as a hobby machining and a challange to recondition my lathe to make it more accurate and any advice and help I get is appreciated
B the B
19th Oct 2009, 12:20 AM #6Dave J Guest
There are a few threads on making acme screws and nuts on that site, it might be worth a look if you need more info. Just type in acme thread in the search box and you will get 20 pages of results on the topic.
19th Oct 2009, 08:36 AM #7
No probs B the B
Do you definitely want to make your own? or would you rather buy replacements? Do you need both screw and nut? Does your lathe have power cross feed, i.e. is it a model A or B?
You should be able to buy them. Is the spigot ontop of the nut 11/16" diameter? That is the size on the Southbend and Hercus. There is someone in the States who sells pieces of precision rolled acme thread he had specially made for this. You cut your old thread off, then drill bore and ream a hole there and stick the new piece of thread in with loctite.
I reckon it shouldn't be too hard to find somewhere to buy a Hercus or Southbend nut.
How bad is what you have? What degree of backlash will you be happy with?
20th Oct 2009, 02:22 PM #8
A new leadscrew and nut from a commercial source is quite economic.
The downside is that you get a length of screw - you have to machine and add to taste.
I have purchased from TEA in QLD and the specifications for the screw and nut match what you will get with a new lathe.
TEA was recommended to me by a machine reconditioning company in Sydney.
I am in Sydney with a Sheraton 9A.
My screw and nut are for a Tom Senior M1 horizontal mill refurbishment.
20th Oct 2009, 11:13 PM #9
screw and nut for sheraton lathe
I might take the easy option by buying from the queensland place you mentioned but am not familiar with the TEA place you mentioned thanks
B the B
4th Nov 2009, 09:06 PM #10
Yeh it seems that i am in the same boat as you B the B .If you do happen to find some place that has the thread i would much appreciate the contact details .I must admit that i have not started looking for a new thread as i have only just pulled apart my slide to discover why it was so sloppy.Seeing this thread was a bonus
4th Nov 2009, 09:22 PM #11
I took the plunge and obtained some acme taps. Tried a number of places, found these
people reasonable:Tracy Tools :: Devon, UK
They cost 18 pounds each and worked fine. A place in the US quoted $200+.
PS This was for a sheraton 9". (the 10" lather model has a metric thread)
4th Nov 2009, 10:09 PM #12
I am in the process of trying to cut my own thread and am doing as much home work on it as I have time for have cut a trial piece of thread about 50 mm long and it looks good have sourced a piece of steel from the local engineering shop (good to keep these guys on side without being a pest) that I will make an acme tap from temper and harden it ,then make the nut and finally make the screw thread for the cross slide sounds easy but like all things there will be obstacles allong the way half the fun is not the destination but the journey along the way
cheers dude09 and have a go at making one yourself
5th Nov 2009, 06:44 AM #13
Normally i would have a go at making one but haven't the time or skill level at this stage. Like yourself and a lot of others its the challenge and satisfaction when things turn out right. This i do know, my skill levels at the moment are still on the bottom row but over time that will change. At the moment i read some of these bloody threads and think how the hell did he make that. I like to think maybe one day someone will say that about something i have made but i doubt it. Hope everything turns out well B the B, will keep reading to see how its turned out for you.
18th Nov 2009, 12:36 AM #14
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