Acme Thread Tap Required, Please check your tap box....Numpty Alert...

[zzr1200]

Having purchased my L6 I now need to replace the top and cross slide screw nuts, not a problem, I'll measure the threads and order the taps.

The top slide is 1/2" x 10 tpi Acme Tracey Tools supplied a perfect tap.

I also needed a 5/8" x 10 tpi Left Hand Acme tap for the cross slide nut this time RGD Tools supplied the tap. Again exactly what I ordered.

And now how I officially become a Numpty...........its simple, what I didn't notice is that the cross side screw is Twin Start Acme Thread, so what I actually need is a

"5/8" x 10 tpi Left Hand 2 Start Acme Thread Tap"....... (or better known as "A Rocking Horse Poo Tap")

I've been in touch with Tracy Tools they only have " 5/8" x 10 tpi Right Hand 2 Start Taps" on the shelf, they can get one made to special order, don't even ask!!!!


So those of you who may have that old box of boot fair maybe useful one day thread taps , any chance of brushing the dust of and having a rummage, Please.

Feel free to extract the ..................

 

[MattH]

Ping Tom Lipton on YouTube a message. He has a number of special Acme taps that he holds to lend out worldwide.

 

[ford34/2]

I dont hold out a lot of hope, not so long ago I wanted a metric cross slide nut for the boring table attachment, on a 140, first thought like you, was buy a tap, having totally exhausted that possibility I had a good look and contacted several companies with regards to supplying a ready made blank that I could adapt, however the few that replied could only do a single start L/H part. It came down to buying some drelin and swatting up on making a one by cutting the desired part in two heating up a male threaded part and clamping the delrin over it to seal back together and form a perfect thread. By chance G&M Tools advertised a metric nut and shaft as being metric when it came it was imperial, after returning it and enclosing a drawing they found a metric one--brand new unused. I still have the delrin ---- another unfinished future project to try out one day. Contact G&M they had imperial stuff, be prepared to explain sizes and what one full turn of the screw means in thou. They may well fix you up.When I bought mine it was advertised as a part for an L16 or something anyway much bigger lathe than the L5A 140,11"-- however the gamble paid off as the part was a direct swap. Perhaps like me take a gamble --buy it ----they will refund full price if you pay to send it back.
If not some reading:
http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way

Stan

 

[Dee J]

You've got a lathe with a working top slide... so lock up the cross slide solid and get turning. Either make a tap using a medium carbon steel - which should be ok for a bronze or grey cast nut... or turn the nut direct. Tooling will take a little thought... and you'll need to get a reverse into the leadscrew gear train... but for the sake of a little time and a few bits of scrap you may already have the answer.

 

[AndyStobbs]

I've bought a brand new L16 feedscrew and nut (imperial) and its the same thread. I'm going to replace the feedscrew and the nut and as the feed screw is longer than needs be, the length I cut off the end will be a perfect tap once fluted.

 

[Maker]

My chipmaster can cut reverse and multi start threads, I'll have a go at cutting one this weekend and if it comes out nice I can make your nut if you want.

 

[Wendelspanswick]

I cut a new cross slide nut for my Colchester Student by locking the cross slide and using the compound slide to advance the boring bar.

 

[zzr1200]

I've ordered a L15 imperial cross slide screw/nut from G&M Tools, I'll take a chance on the nut fitting on my cross screw/slide...

My cross slide screw...

 

[Shox Dr]

The crossfeed screw on the M300 was badly worn. I converted it to Ballscrew (1605), I now have zero backlash.
All for less than 40quid

I can also dispel the myth of Ballscrews walking under heavy cuts. Unless there is something stopping it (DCmotor) from turning. I certainly cannot induce any, the 1 micron reader on the cross feed confirms no moment.

The Tom Senior LV is getting the same treatment at the moment

 

[I'm getting on a bit]

I can also dispel the myth of Ballscrews walking under heavy cuts. Unless there is something stopping it

It's not a myth.

 

[zzr1200]

You've got a lathe with a working top slide... so lock up the cross slide solid and get turning. Either make a tap using a medium carbon steel - which should be ok for a bronze or grey cast nut... or turn the nut direct. Tooling will take a little thought... and you'll need to get a reverse into the leadscrew gear train... but for the sake of a little time and a few bits of scrap you may already have the answer.

The only problem with that idea is I have yet to install the 3 phase inverter, wire it up and set up the parameters. All jobs for this weekend hopefully, unless SHMBO has other ideas...


So actually thread cutting/turning is not an option at the moment.......hence old fashion taps...

 

[AndyStobbs]

The L15 screw wont fit direct but when I looked at mine (on the L5A) it's just a case of making a sleeve and joining the back half of the L15 screw to the front half of the L5A screw.
Well worth having a brand new thread and nut, as when you run a brand new nut up an old screw you get an appreciation of the wear on the feedscrew.

 

[Shox Dr]

It's not a myth.

I must have dreamt it then

 

[brewdexta]

The crossfeed screw on the M300 was badly worn. I converted it to Ballscrew (1605), I now have zero backlash.
All for less than 40quid

I can also dispel the myth of Ballscrews walking under heavy cuts. Unless there is something stopping it (DCmotor) from turning. I certainly cannot induce any, the 1 micron reader on the cross feed confirms no moment.

The Tom Senior LV is getting the same treatment at the moment

Pictures please Dave
I may do something similar.

 

[I'm getting on a bit]

I must have dreamt it then

I don't doubt you have not experienced it. But it could be caused by mis alignment excessi ly tight gibbs who knows.

 

[zzr1200]

The L15 screw wont fit direct but when I looked at mine (on the L5A) it's just a case of making a sleeve and joining the back half of the L15 screw to the front half of the L5A screw.
Well worth having a brand new thread and nut, as when you run a brand new nut up an old screw you get an appreciation of the wear on the feedscrew.

My cross slide screw isn't the standard screw assembly anyway as its splined for the taper turning attachment (picture above), so I will have to have a look when it arrives.

I can see a bit of modifying, I reckon I might have to "cut n shut the screw twice".

 

[Shox Dr]

I don't doubt you have not experienced it. But it could be caused by mis alignment excessi ly tight gibbs who knows.

I do. Neither are tight or misaligned.

 

[Shox Dr]

The Tom Senior LV is getting the same treatment at the moment

Pictures please Dave
I may do something similar.

It's still on the floor Andy. Daft thing is it wouldn't take much to finish it.
I'll have a job for it, then I'll finish it

 

[zzr1200]

My new cross slide screw and nut arrived today just have a bit of cutting n shutting to do.....

The left hand one has to made to look like the right hand one...

 

[AndyStobbs]

Yeah but how nice is the fit up between nut and screw, it'll be worth it.