First threads on lathe

[phil1962Participant @phil1962]

 

hi fellas cut my first thread on my lathe today after getting my cutters sorted what do you think its 20 tpi same as gun barrel I am pleased to bits I managed to do it set gears as the chart said over the moon never used a lathe before   

Edited By phil1962 on 10/03/2017 19:51:12

[phil1962Participant @phil1962]

[phil1962Participant @phil1962]

can not add pic

[Andy HoldawayParticipant @andyholdaway]

Phil, Well done on your first thread. I cut my first one in 40 years a couple of weeks ago – it's a great feeling when it works!

For posting pictures see this thread.

Andy

[Neil WyattModerator @neilwyatt]

Well done Phil, in at the deep end

Neil

[Nick_GParticipant @nick_g]

Posted by phil1962 on 10/03/2017 19:38:55:

its 20 tpi same as gun barrel

.

If you are talking about a sound moderator on a small caliber rifle yes many are 1/2" x 20 (though a small number are metric)

Hope you dialed the bore in and not the outside diameter. – The bore is seldom in the middle.

Nick

[phil1962Participant @phil1962]

Posted by Nick_G on 10/03/2017 20:06:09:

Posted by phil1962 on 10/03/2017 19:38:55:

 

its 20 tpi same as gun barrel

 

.

If you are talking about a sound moderator on a small caliber rifle yes many are 1/2" x 20 (though a small number are metric)

Hope you dialed the bore in and not the outside diameter. – The bore is seldom in the middle.

 

Nick

hi yes I hope to thread my own barrels one day when I get the hang of it lol

Edited By phil1962 on 10/03/2017 20:38:27

[Neil WyattModerator @neilwyatt]

Posted by phil1962 on 10/03/2017 19:51:28:

can not add pic

See the top thread on the FAQs topic: http://www.model-engineer.co.uk/forums/threads.asp?t=145

Neil

[VicParticipant @vic]

One of the things that prompted me to buy a lathe was to cut a thread for an Airgun charging adaptor. The thread turned out fine except it didn't fit – wrong thread pitch. I set the gear wheels according to the chart on the lathe but the chart turned out to be incorrect. Just my luck! My second attempt using the thread cutting chart in the manual was fine. This was the second job I did on the lathe and I'd never cut a lathe thread either. The first job though was to make a reduced size motor pulley to slow the lathe down as the slowest speed was about 190 rpm, a bit fast for thread cutting. I managed to get the speed down to about 100 rpm.

[JAParticipant @ja]

I remember the first time I cut a thread on a lathe. It was in the apprentice training school and being mechanical engineering apprentices we weren't really expected to master such things. Anyway I decided to have a go and was quite happily cutting something like a 1/2" BSF thread when some VIP visitors came round. They decided to stop and have a chat. I smugly twiddled the controls of the lathe and they went away smugly satisfied. I then carried on cutting the thread only to find that the lead screw t.p.i. was now incorrectly set.

Never trust visitors however important.

JA

[Allan BParticipant @allanb]

I am just messing around with cutting my first threads on a lathe too, only issue I’m having at the moment is on my myford lathe, with the screw cutting gearbox, it only cuts imperial threads, and all my nuts are metric so they don’t match 🙁 so just bought internal and external cutters and will have a go at making some matching threads for the fun of it lol

Allan

[jimmy bParticipant @jimmyb]

Next step is screw cutting to a shoulder!

[phil1962Participant @phil1962]

[phil1962Participant @phil1962]

my first thread on lathe never done it before do you think it looks ok scrap bit of brass

[Allan BParticipant @allanb]

Looks good to me, better than my first attempt 😀

[phil1962Participant @phil1962]

one problem I had was the cutter the tip was small and had trouble using the fish tail is there another way to set it up so its straight ?

[Neil WyattModerator @neilwyatt]

Posted by Allan B on 11/03/2017 07:51:59:
I am just messing around with cutting my first threads on a lathe too, only issue I'm having at the moment is on my myford lathe, with the screw cutting gearbox, it only cuts imperial threads, and all my nuts are metric so they don't match 🙁 so just bought internal and external cutters and will have a go at making some matching threads for the fun of it lol

Allan

See this thread:

http://www.model-engineer.co.uk/forums/postings.asp?th=71014

Neil

[Neil WyattModerator @neilwyatt]

Posted by phil1962 on 11/03/2017 08:55:38:

one problem I had was the cutter the tip was small and had trouble using the fish tail is there another way to set it up so its straight ?

If it's an accurate holder teh tip should be aligned with the shank, just use a square between the work and the side of the holder.

Neil

[Ian S CParticipant @iansc]

With the cutter you are using, and assuming the end of the bar is squarely faced, move the tool in front of the bar(lathe stopped), and square the two against each other, no fishtail or square needed, takes about 10 seconds.

My recommendation is use HSS, learn to grind your own.

Ian S C

[Allan BParticipant @allanb]

Thanks for that Neil, I have looked at the metric conversation set, but at ?290 for the set, and just finding out I have been made redundant, I can’t justify spending that much money at the moment, but it is on my list of future purchases.

[Chris Evans 6Participant @chrisevans6]

"First job was to make a reduced pulley to slow the lathe down".

I must agree, what is it with lathe manufactures and slow speeds ? My lathe minimum is 82 RPM this is OK on something like 20 TPI but scary when cutting a course pitch around 3mm. I have considered getting the motor off and finding the star point so that I can run off a VFD and use it to slow things down, doubt I will ever get round to it though.

[Allan BParticipant @allanb]

this was my first attempt, the smaller side is 8mm diameter with a thread, the other end is 10mm diameter with almost a 1.5mm pitch, its actually 16TPI which comes out at 1.588mm pitch, so the M10 nut will only go on by a few threads

[BazyleParticipant @bazyle]

Posted by Allan B on 11/03/2017 09:50:27:
Thanks for that Neil, I have looked at the metric conversation set, but at ?290 for the set, and just finding out I have been made redundant, I can't justify spending that much money at the moment, but it is on my list of future purchases.

You don't need the expensive metric conversion set. Didn't check which thread Neil linked but for the Myford there is a thread showing details for metric conversion (approximations) that only uses one small gear change so very much cheaper. JS makes the gear so possibly sells it through ARC. Read the whole thread and follow the later link by JohnF.
If you are not using the angled topslide method (lets not go into arguing about that) when you are using an approximation and the nut is tight just put in a small extra cut with the topside moved along a few thou and you will get clearance. Yes a tad weaker thread but in non stressed parts it's ok.

[phil1962Participant @phil1962]

Posted by Ian S C on 11/03/2017 09:44:06:

With the cutter you are using, and assuming the end of the bar is squarely faced, move the tool in front of the bar(lathe stopped), and square the two against each other, no fishtail or square needed, takes about 10 seconds.

My recommendation is use HSS, learn to grind your own.

Ian S C

cheers will try that out thanks

[Peter Wood 5Participant @peterwood5]

I have also just made my first attempts at screw cutting with limited success.

However when working out how to use the QC gearbox on my S7b I recalled that the lathe came with a loose set of gears. There are eight in total numbered 30, 35, 38, 40, 45, 50, 55, and 60.

Can anyone tell me what they are for?

[Author]

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