Tap for 1/2" x 2mm acme

[Paulbarrett]

have a busted topslide nut from my harrison, also worn.

I bought a new nut from G and M, but it is totally different. Taller and left hand thread, prob imperial too.


I have the above as measurements, anyone have a tap i could borrow

 

[Spark plug]

1/2" x 2mm are you sure? Does the lathe have metric or imperial dials?

 

[Paulbarrett]

Scewbneasure up 0.499". Threads measure up 2mm, granted that's with a 60degree gauge but perfect fit

 

[Spark plug]

How are the graduations marked on the dial? 1-1.5-2 etc or 10-20-30 etc.

 

[Paulbarrett]

0.2-0.4-0.6.....

 

[Spark plug]

0.2-0.4-0.6.....

Well that sounds like metric, just sounds odd haveing a metric pitch with an imperial OD.

I have no idea ware you would find a tap. Is it a 10deg acme thread?

 

[ford34/2]

which Harrison Lathe??

Stan

 

[Paulbarrett]

It is a Harrison l5

 

[ford34/2]

If the dials on the cross and compound are metric, it will be a metric thread, if the dials are imperial they will of course be imperial TPI. Note cross slide on a metric machine is a twin thread possibly will be on an imperial machine as well.
I can check my 140 -its metric if that might help???

Stan

 

[Wendelspanswick]

If you lock the top slide you can use a boring bar to cut the thread, advance the cutter with the compound slide. That's how I cut a new nut for my Student.

 

[Paulbarrett]

Aha, I think your pdg

 

[Shox Dr]

FWTW.
My M300. Is LHD ACME 5/8x10.

I needed to replace the crossfeed screw. Converting it to Ballscrew instead, Cost less than £100, and is a pure delight to use.

It's also Dual dial. The Imperial dials reading directly, the Metric via a 127 tooth wheel inside the handle so is off a tad

 

[Paulbarrett]

Right? . Really should stop using an iphone to type,

 

[ford34/2]

I can give you some Delrin to "cast"a new nut off the shaft, Need a size please.
http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way

Stan

 

[Paulbarrett]

I have some Delrin from when I attempted a new nut for the mill, not having much luck with acme nuts!

 

[Paulbarrett]

 

[Paulbarrett]