Thread: Need parts for lathe

Anyone?

got a vague idea you might be able to get acme in allthread but dunno where. Maybe one of the cnc fellas might know

Originally Posted by echnidna

got a vague idea you might be able to get acme in allthread but dunno where. Maybe one of the cnc fellas might know

can you name any cnc fellas in sydney??

Bart,

I have a similar problem with my old Brackenbury and Austin lathe and it has been suggested by my machinist neighbour that it should be possible for me to manufacture replacements, actually he made it sound fairly straight forward .

A quick search on Google Australia for "acme thread" yeilded these.......:

http://www.mecco.com.au/acmescrew.html

http://www.hotfrog.com.au/Companies/Acme-Thread

Also, look up rodm here on the forums as he has made a number of CNC machines and may know of some suppliers.

I actually rang http://www.hareandforbes.com.au/sample_2/home.php and he suggested i should come in and try to match something similar off the shelf and get it machined up a little if need be.
I also rang a tool maker and he basically said the cost to do the job would be extremely expensive because of tooling cost etc etc, i think in other words he wasnt keen on doing such a little job as it wouldnt generate too much profit for him, thats how i read it, fair enough.
I have seen mecco but i havnt got in touch with them yet, at this stage ill go for the advice Hare and Forbes gave me and see if i can find something close match.
Ill go for Hare and Forbes and keep you guys posted on what happens
thanks for your feed back.
Ill post pics if i buy the bits.

I just cam accross this page, where the guy had some screws made up.
Look down the page a bit, and you will see he has provided a link.
http://www.gimbal.com.au/content.asp...nc-mill-design

Good luck.

Hi Bart,
I have two sugestions

It could be costly for freight but www.enco.com in the states, have a range of Acme Thread and nuts. I had a friend buy it and when I visited brought a 3ft and 6ft length back as luggage.

The other is if the lathe is working and is capable of screw threads then use the lathe. Less accurate machine tools can be setup to make more accurate pieces if caerefully used. It may be greater than my capability but you may be better. I have a new lathe that would be capable of the job, but I'm not. I've only had it for two months.

Cheers

thanks outsider i may have to do that, i still have to go to Hare & Forbes and check them out, i may go to your route tho if failing other options.
My lathe is pretty bad, it shudders etc i wouldnt want to risk it and bugger up a nice bit of bronze and steel.
Ill see what happens hopfully tomorrow i will see Hare & Forbes
thanks guys

hey guys, after heaps of rooting around on how to do what about buying acme threads and nuts and or getting them made, i have branched off and thought i may as well give it a go and make it myself . I hope
Hare and Forbes couldnt realy help in terms of supplying parts but they gave me a few ideas etc.
The plan is to use a standard mild steel threaded rod and nut, weld a pedastal under the nut and mount it on the cross feed slide as where the original cross feed nut would be. I estimate this will be enough just to get it going.
The compound slide thread is sloppy also, but this may be barley good enough to have a functioning lathe, this will hopfully enable me to make up an acme thread and nut of correct tpi and diameter etc. Perhaps i could give the compound nut, (the compond nut is one piece cast on the compound slide not seperate) a fews taps with a hammer to tighten it up a little, in affect shrink the thread/nut a little, i know this is dodgy as hell but may help with tightening things up a little temporarily. This is temporary to enable me to make the acme thread and nut for the cross feed.
At this stage i should have the acme screws, cross feed and compound, and a cross feed nut, so i can now mount the cross feed nut and cross feed lead screw.

Now the other part which could be a little tricky, i need to weld up the thread in the compound slide and re drill, re thread it with an acme thread.
What sort of weld should i use?? since the material is cast steel, or would it be cast iron?? It could become brittle after welding?? which is not desirable.
Can anyone help with the welding question? I have a MIG but i was told if welding cast steel or was it casr iron i should use an arc welder with a cast steel grade rod, is this correct??

Or theres this

www.rockfordballscrew.com/acme.htm theyre in the US

Originally Posted by Bart

Now the other part which could be a little tricky, i need to weld up the thread in the compound slide and re drill, re thread it with an acme thread.
What sort of weld should i use?? since the material is cast steel, or would it be cast iron?? It could become brittle after welding?? which is not desirable.
Can anyone help with the welding question? I have a MIG but i was told if welding cast steel or was it casr iron i should use an arc welder with a cast steel grade rod, is this correct??

Hey Bart,
I don't think trying to weld the cast iron and re-cut the thread is going to be very successful.......I think my approach would be to cut a seperate "nut" with the acme thread in the centre, and a round external body, probably out of bronze. Then drill out the "original thread" in the compound slide to the O.D. of the new "nut", then, insert new "nut" in hole and loctite into place using super retaining compound. To make sure it doesn't move I'd add a couple of pins which would be drilled through the cast iron, and would pick up the edge of the "nut" when hammered into place.
Just my 2c worth if had to do it....
Karl

Originally Posted by Fiatnut

Hey Bart,
I don't think trying to weld the cast iron and re-cut the thread is going to be very successful.......I think my approach would be to cut a seperate "nut" with the acme thread in the centre, and a round external body, probably out of bronze. Then drill out the "original thread" in the compound slide to the O.D. of the new "nut", then, insert new "nut" in hole and loctite into place using super retaining compound. To make sure it doesn't move I'd add a couple of pins which would be drilled through the cast iron, and would pick up the edge of the "nut" when hammered into place.
Just my 2c worth if had to do it....
Karl

Your 2c is quite valuable mate thank you.
On the other hand i can lock up the compound slide by bolting it together, this will make the compound non functional which would be good enough to cut a thread into some steel rod and make the compound and cross slide nuts.
I think i can nail it

I did a bit of research on welding cast iron and its recomended using hi nickle grade arc welding rod. Or http://www.muggyweld.com/castiron.html

Ok i was thinking of using 4340 rod for the lead screws, the nuts will be bronze, is 4340 ok in your opinions guys??

I am not trying to rain on your parade but:

If you try to weld a cast iron thread with stick electrode it will fail, no question about it what so ever.


I have years cast iron experience and it is one job I would not attempt it that way.How do you know it is cast iron ?.

Have you done a spark test? Try grinding it some where it won't affect it. It should give you short red sparks without sprigs (branches) if it is cast iron.
If it is cast iron, which one of the several different types is it?

Cast iron sucks up all manner of contaminants, so your in for a hell of a time welding and machining it. It will never be be in alignment as one of the other nasty charecteristics of welding cast iron is the distortion.A shaft is one of the most difficult to keep straight. It acn,t be simply presseed straight again it is not flexible or malleable.
If the screw can't be replaced and must be built up use one of the brazing rods - maganese based from memory - to give a wear resisting build up.

First up I would seeking advice from someone who does machinery restoration, there are such people around.

My apologies that I sound so negative, but in my minds eye , I can see a lathe that will have to be scrapped unless you find some one who knows what they are doing.

It is one thing to save money and do it your self,buquiet another to take on something which may be beyound your level of experience and expertise.

Grahame