Author Topic: Next level on the lathe  (Read 12139 times)

franco

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Re: Next level on the lathe
« Reply #30 on: 01 November, 2018, 07:37:26 pm »
QUOTE: I have taken some pics of my dial that happened my way but it is listed to suit another brand of lathe,  a Sieg C2, C3, SC2 & SC3 and I have no idea of the size off the lead screw on those machines.

Mr Google tells me that the Sieg C3 leadscrew is 1.5 mm pitch.

Frank.
Cairns, Queensland

franco

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Re: Next level on the lathe
« Reply #31 on: 01 November, 2018, 08:11:55 pm »
QUOTE: I did buy some HSS with the intention of grinding it to shape but have not gone down that road as yet.

If you are cutting threads at your minimum spindle speed (I think you said 60 RPM?),  which is sensible when starting out, I suspect you will get much better results using a sharp HSS tool rather than a carbide one, which performs better at higher speeds where everything happens more quickly.

You can learn an awful lot about the details of operating a basic lathe if you get a copy of South Bend's "How to Run a Lathe" or Sparey's "The Amateurs Lathe", both readily available on the internet new  or second hand. The commonly available new reprint of "How to run a Lathe" is of a fairly old edition, but all the basics are there.

Frank.
Cairns, Queensland

cobbadog

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Re: Next level on the lathe
« Reply #32 on: 02 November, 2018, 02:37:55 pm »
Thank you for the ongoing help here. I think my head is getting around it and my next step is to source some gears to suit the more common metric threads I use. Then I thought that maybe, just maybe once I work out what size gear and how many teeth it might be able to made on a 3D printer. Any thoughts on this idea?

 
Cheers, John & Dee. Coopernook. NSW.

franco

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Re: Next level on the lathe
« Reply #33 on: 02 November, 2018, 06:02:24 pm »
QUOTE: once I work out what size gear and how many teeth it might be able to made on a 3D printer. Any thoughts on this idea?

Sounds as though it would be well worth a try for gears for occasional use, since very little power is needed to drive the indicator.  FWIW I just had a look at the indicator on my imperial lathe, which has an 8TPI leadscrew, which is close to 3 mm pitch, and the gear is just a straight toothed pinion with teeth 10 mm wide. The teeth appear to be cut a bit deeper than the common spur gear form used for the lathe gears. The whole gear is very roughly finished, so obviously no great precision is required. I can't see on my thread indicator without pulling it apart if it's spindle is tilted to the helix angle of the leadscrew. I suspect it is though, to give a bit more tooth contact with the leadscrew, which I think might be a good idea with a plastic gear.

It will be interesting to see how you go with this - don't forget to keep us informed!

Frank.
Cairns, Queensland

cobbadog

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Re: Next level on the lathe
« Reply #34 on: 04 November, 2018, 02:54:32 pm »
Will keep you informed as I progress. Have just posted a question on a model forum that has a 3D printer section and asked them what their thoughts are on a printed gear for my application.
Some of the gears I have seen stacked on top of one another and then you would undo a set screw and lift or lower the dial to engage a different size gear. Cleaver idea but I will look at changing the gear over to the next size and have each gear attached to it's own small shaft that screws into the dial. The lot will pivot on its own axis to engage the lead screw or I can leave it engaged permanently, yet to be decided.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: Next level on the lathe
« Reply #35 on: 08 December, 2018, 03:46:29 pm »
OK,
This is where I am at.
I have 3 gears at the moment all will be suitable for doing metric threads. Then the research for the size gears needed for doing Imperial will be next.
I am making the thread chasing dial from scratch and have most of it machined up with a little more to do tomorrow then it can be assembled and adapted to the lathe.

I will take pics tomorrow to show you the mess I'm making!   8)   :o
Cheers, John & Dee. Coopernook. NSW.

franco

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Re: Next level on the lathe
« Reply #36 on: 09 December, 2018, 02:07:50 pm »
Then the research for the size gears needed for doing Imperial will be next.

Hi John,

This can't happen. I say again:
If you have a lathe with a metric leadscrew you can use the thread dial indicator to cut metric threads provided you have the right gear for the required pitch. You cannot use the thread dial indicator to cut imperial threads with a metric leadscrew, but need to leave the half nuts engaged.


Regards,

Frank.
Cairns, Queensland

cobbadog

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Re: Next level on the lathe
« Reply #37 on: 09 December, 2018, 04:37:23 pm »
Yes Frank and thanks for that.
This is what I have made and have gears to suit the metric threads I want to do as a beginner. Also got some Tefolex to put on the metal to aid the cutting process.
Mr Chinaman seller of the gears told me that the gears I chose would engage correctly to a 20mm OD lead screw with the 3mm pitch and he was correct.
I assembled hat I made and bolted it onto the lathe and gave it a run to ensure that it did rotate when the carriage is not moving and stopped when the half nuts were engaged just like the real thing.
Ran out of time today to do the marking up of the dial so will do that next chance I get so I put a bit of paint on my achievement and will continue with the project soon.
you can see the gears and the mounting bolt in one pic, all the components in another and a coat of paint on the body, not mine.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: Next level on the lathe
« Reply #38 on: 12 December, 2018, 04:24:22 pm »
In place and working.

I still want to print out a face for the dial as it would look far better, but at least this is working as planned out in my little head.

I was just reading in a book named  'Screwcutting in the Lathe by Martin Cleeve. Workshop Practice Series #3 and there is a whole chapter on how to cut imperial threads using a metric lathe. I read this and it is some scarey reading and possibly only for those who do understand all the principles in lathe work. May at a later date I can try to take it onboard and understand it better but the algebra is way up there.
With a leadscrew pitch of 3.00mm = (15 x TPI)/127.
Cheers, John & Dee. Coopernook. NSW.

asw120

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Re: Next level on the lathe
« Reply #39 on: 16 December, 2018, 04:19:57 pm »
If it's any use; my poxy little Chinese lathe mill is all metric, but has an imperial adaptor gear with two gears side by side (like 1st / 2nd sliding gear in an old gearbox). One has 125 teeth, the other has 127.
I don't know what's inside yours, but mine I have to remove and replace gears to change the feed speed / thread pitch.

Jarrod.

cobbadog

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Re: Next level on the lathe
« Reply #40 on: 17 December, 2018, 04:03:28 pm »
Hi Jarod,
Yes I have the 127 tooth and I think the 120 as well. I have the option of ganging 4 gears (1-2-1) together to get various ratios. That is one gear on top 2 on then idler shaft  and 1 gear on the lead screw end.
It is amazing how many variants there are with these gears. I am guessing I have about 10 gears all up and some are duplicated in teeth numbers and they all be be mounted in different positions.

If I go down the road of wanting to do imperial I can get more gears for the dial to match the pitch I want, but that will be some time yet.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: Next level on the lathe
« Reply #41 on: 18 December, 2018, 03:59:30 pm »
May not look the prettiest but at least it does work.
Cheers, John & Dee. Coopernook. NSW.

ianoz

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Re: Next level on the lathe
« Reply #42 on: 22 December, 2018, 10:08:19 am »
Saw this and thought of this thread .Merry Christmas Cobba
fowler vf,david brown 30td,cat D24U,D47U,D47J,D46U,R4,D68U IH TD9,TD6 and many more
 Benaraby Central Queensland

cobbadog

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Re: Next level on the lathe
« Reply #43 on: 22 December, 2018, 04:43:40 pm »
Hi Ian, that looks like one of those 'multi purpose' chucks. Hopefully it is self centering!  ::)
Cheers, John & Dee. Coopernook. NSW.