What Did You Do Today (2017)

[Clive HartlandParticipant @clivehartland94829]

Very impressive Joseph, conservation is ongoing everywhere now and as African nations realize the value of their Flora and fauna. Obviously Namibia is a special case as living conditions are hard for the desert animals.

Clive

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for the post, Joe

… Very interesting work !!

MichaelG.

[Anthony KnightsParticipant @anthonyknights16741]

Hi there Roy and Ian

Printer is an EPSON SX400. I didn't really want to identify the make as I was slagging it off. I'm pretty sure the ink monitoring software is bent.

Edited By Anthony Knights on 14/08/2017 08:58:59

[Neil WyattModerator @neilwyatt]

Joe,

The 'engineering related' is widely ignored, this is where people share their everyday stories. The 'workshop progress thread' is the one where off topic posts get shot down

I find the work you are doing fascinating – very different from conservation in the UK!

Neil

[Cornish JackParticipant @cornishjack]

Joseph – your previous posts re. machinery/tool refurbishment have left me hugely impressed and wondering how you manage to fit in any other activity. This latest collection of interests, innovations and breadth and depth of enthusiasms leave me absolutely mind-boggled. Any one single instance of your range of efforts would more than satisfy me (were I capable!) but the sum of your achievements is just staggering. Many congratulations and long may you continue.

Very best regards

Bill

[Steve PaveyParticipant @stevepavey65865]

Posted by Anthony Knights on 13/08/2017 21:37:12:

I've just tried printing some sections of interest to me from the "gunsmith" pdf that was linked to recently. Strangely, trying to print odd (or even) pages results in alternate ones being missed.

It's probably to do with how the PDF file was set up initially. The page numbers of the original document don't necessarily reflect the pages that the PDF writing software generate. If you have some PDF software (like Adobe Acrobat) you could probably sort it out using the page setup menu. But for just one document, being printed just the once, it might be better just to work round it.

[Swarf, Mostly!Participant @swarfmostly]

Posted by Neil Wyatt on 11/08/2017 15:00:39:

Well done Nige,

If you don't angle the cross-slide, move the top slide left by a bit less than half as much as the extra cut depth (e.g. infeed 4 thou, side ways 2 thou).

This will keep the tool cutting on only one side, making things a bit easier.

Neil

Regarding the setting over of the top-slide for screw-cutting, am I the only one who's noticed Tubal Cain's observation (see 'Simple Workshop Devices', page 62) that we're all setting the slide over the wrong way?!?!

He writes that for a right-hand male thread, 'the left-hand flank of the thread cannot touch its mating thread'. So it's the finish on the other flank that's important.

Best regards,

Swarf, Mostly!

[Tony JeffreeParticipant @tonyjeffree56510]

Not exactly a model, or engineering, but it does involve a workshop. I've been working on a 12' rowing boat kit for the last few weeks & making good progress:

The bottom is glassesd and coated in resin, ready for sanding, filling, and painting. Still work to do on the inside – more pics when I turn it over again.

[Anonymous]

Posted by Swarf, Mostly! on 14/08/2017 10:26:12:

Regarding the setting over of the top-slide for screw-cutting, am I the only one who's noticed Tubal Cain's observation (see 'Simple Workshop Devices', page 62) that we're all setting the slide over the wrong way?!?!

Not me, I don't bother setting the top slide either way. I just leave it parallel to the lathe axis and use the cross slide to directly read thread depth.

Andrew

[Martin KyteParticipant @martinkyte99762]

Posted by Swarf, Mostly! on 14/08/2017 10:26:12:

Posted by Neil Wyatt on 11/08/2017 15:00:39:

Well done Nige,

If you don't angle the cross-slide, move the top slide left by a bit less than half as much as the extra cut depth (e.g. infeed 4 thou, side ways 2 thou).

This will keep the tool cutting on only one side, making things a bit easier.

Neil

Regarding the setting over of the top-slide for screw-cutting, am I the only one who's noticed Tubal Cain's observation (see 'Simple Workshop Devices', page 62) that we're all setting the slide over the wrong way?!?!

He writes that for a right-hand male thread, 'the left-hand flank of the thread cannot touch its mating thread'. So it's the finish on the other flank that's important.

Best regards,

Swarf, Mostly!

George Thomas recommends setting to slightly less than half angle so that the trailing flank is just cleaned up by the tool. He said that the curl of swarf coming from the leading flank can touch and then rub on the trailing flank and mess the finish up. It also prevents the oversetting of the half angle resulting in a wider V.

regards Martin

[Martin KyteParticipant @martinkyte99762]

Are you using inserts Andrew?

regards Martin

[Jon GibbsParticipant @jongibbs59756]

Posted by Swarf, Mostly! on 14/08/2017 10:26:12:

He writes that for a right-hand male thread, 'the left-hand flank of the thread cannot touch its mating thread'. So it's the finish on the other flank that's important.

I can't say that I'd noticed much difference in finish between the two sides of a thread. After all I thought the idea was that the intent to use a lower angle than 30/27.5 was to ensure that the right hand flank was "cut" on every pass too? It might be my inexperience though.

Martin Cleave (Screwcutting in the lathe – WPS No 3) addresses the topic on page 157 (poor finish) and says that it may be due to "too pedantic following of top slide advancements" or the tool not set to cut on the trailing edge.

Jon

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Martin Kyte on 14/08/2017 10:52:06:

George Thomas recommends setting to slightly less than half angle so that the trailing flank is just cleaned up by the tool. He said that the curl of swarf coming from the leading flank can touch and then rub on the trailing flank and mess the finish up. It also prevents the oversetting of the half angle resulting in a wider V.

Yes, he recommends setting the slide over by 25° for W.W. threads for that reason. The feed in required is then 1.1 times the true thread depth.

Russell

[MuzzerParticipant @muzzer]

I thought most "experts" pointedly recommended a nominal 29 degrees on a 60 degree thread rather than 30 degrees, precisely so that there was a very light cut made on the "other" face. Perhaps TC missed that subtlety.

To my mind, the main reason for setting the topslide over is to reduce the load on the tool, as it is then only substantially cutting on one face. For smaller hobby machines, rigidity is an issue. Trying to cut a large pitch thread by plunging straight in on the cross slide may not always give a happy experience and the swarf doesn't find it easy to come off cleanly from a vee shaped tip.

As a secondary benefit, it also allows you to grind a significant (20-25 degree) top rake on the main cutting edge, which helps to give a clean cut, not only on loominum but also on steel. You'd struggle to grind such an edge on both edges of a 60 degree tool.

Murray

[Martin KyteParticipant @martinkyte99762]

I would concur with Muzzer that the point of setover is to reduce cutting load by avoiding the wedging action at the tip. It also allows the use of simple to grind tools with flat top faces. Top rake is going to mess with the tip angle.

regards Martin

[Anonymous]

Posted by Martin Kyte on 14/08/2017 10:54:28:

Are you using inserts Andrew?

Mostly, but not exclusively.

Andrew

[Michael ToppingParticipant @michaeltopping17870]

I agree with Andrew on this. I haven't set the top slide over for screwcutting for many years. I use a mixture of carbide inserts and HSS tools and I can't say I notice any problem with swarf clearance or damage to the finish. I certainly used this method when screwcutting .25 dia ACME thread recently internal & external.

Michael

[JasonBModerator @jasonb]

I don't set mine over either and use HSS and inserts, maybe it is because the first thread I ever screwcut was a 1/4" x 16tpi square thread and you can't set over for that.

[Jon GibbsParticipant @jongibbs59756]

Duncan and Neil's suggestion (also recommended by Martin Cleave) of half the infeed on the 90 degree set topslide (arc tan 0.5 = 26.6 degrees) also results in the reduced cutting forces and a cut on the RHS of the tool for 55 & 60 degree threads as well as giving direct depth reading. I'm not sure my poor old ML7 would cope with a directly cut thread at 8TPI or 3.5mm pitch!

The method also has the big advantage IMHO that broadening the cut while at full depth is a cinch on either side of the thread crest just by adjusting the topslide.

HTH

Jon

[Iain DownsParticipant @iaindowns78295]

As a matter of interest, do you think I should be able to screwcut an M25 thread on a mini-lathe (Real Bull 0618A, 7×14, 550W motor)?

I was wanting to cut a longish stud for my press (probably about 12 inches). I failed. I tried both the 29 degree set over and the along and in approach.

From memory the bar was held in a 3 jaw chuck at one end and a centre at the other end. Mainly the threading thing seemed to work at the far end but jammed up nearer the chuck when the cuts start to get a bit deeper.

Needless to say I made many cock-ups as part of the learning process and perhaps it would just work if I tried it now. However, I have the impression that a thread of that sizes is a bit on the edge of what a mini-lathe can manage.

Embarrassing though it is, it's one situation in which paying a few pounds for some threaded stud is probably cheaper than the raw material….

Iain

[NigeParticipant @nige81730]

Wow, didn't realise I would set of such a train of comments! Having managed to cut a very poor thread by the 'suck it and see' method I resorted to a Tubal Cain video where he says that 29 degrees is actually the correct angle, for reasons he isn't going in to on an introductory video I guess. I'll not argue with him or you guys about that.

My further investigations show that I got several process's wrong in my first attempt. I had wondered how to get the tool back to the beginning of the thread without it losing 'register' with the thread and my thought process had lead me to bless the existence of the tumbler reverse as that was an easy way to get the carriage back to the beginning without disengaging the half nuts at all! I had to read through 70 plus pages of Martin Cleave's 'Screw Cutting In The Lathe', which was delivered today, to find out that this is a big 'No No' ! I am still trying to work out the reasons why in my head but I'll get there eventually. Looks like a reason too source a motor reversing switch though.

I am waiting on the delivery of a thread gauge as I suspect my MK 1 eyeball method for aligning the tool at 90 degrees to the work may leave something to be desired as tubal Cain makes much of the need for precision in that process.

The dials on the cross slide and compound are not easy to read and are not of the resetable variety and I think I am going to have to write down the value on the cross slide every time before I back it out as I just know I will forget it. Also glad I fitted a thread dial indicator a little while back.

On the thread dial indicator: when I try to engage the half nuts on a particular number the indicator always runs a little past the number and by the same amount. I believe it is possible adjust this out by inserting washers on the stud the indicator is mounted on, I suppose to change its linear relationship to the leadscrew…..does that sound likely?

[MuzzerParticipant @muzzer]

Packing with washers should work, to get the indicator and half nuts to "agree".

If you are cutting imperial threads on an imperial machine, you shouldn't need to reverse the spindle. With a thread dial indicator you should be able to open the half nuts after each pass and reengage them consistently for the next pass.

Sounds as if you are getting there.

Murray

[Swarf, Mostly!Participant @swarfmostly]

Posted by Nige on 14/08/2017 17:08:43:

Wow, didn't realise I would set of such a train of comments! Having managed to cut a very poor thread by the 'suck it and see' method I resorted to a Tubal Cain video where he says that 29 degrees is actually the correct angle, for reasons he isn't going in to on an introductory video I guess. I'll not argue with him or you guys about that.

SNIP

 

Nige,

The 'Tubal Cain' whose book I cited was the late T.D.Walshaw, a Brit.  The 'Tubal Cain' who makes YouTube videos, aka 'Mr. Pete', is an American.

It seems necessary to point this out every so often.

I've got nothing against his videos but I wish he'd done a bit more research before choosing his pseudonym.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 14/08/2017 19:31:31

Edited By Swarf, Mostly! on 14/08/2017 19:32:10

[duncan webster 1Participant @duncanwebster1]

It appears there must be 2 Tubal Cains, or 3 if you count the one in the Bible (instructor of every artificer in brass and iron). TDWalshaw died more than 10 years ago, so I doubt he was making you tube videos, but I might be wrong. It looks as tho the cinematic TC is a yank, in which case 29 degrees makes sense because Unified threads are 60 degree included, whereas Imperial (BSW, BSF, ME, BSP etc) are 55 degree.

In short, don't believe everything you see on You Tube, be a bit critical. And don't pussyfoot around. With my old ML7 which was well past it's sell by date I would take a first cut 20 thou deep, followed by 10 thou cuts until it got near. If you feel you must, use a hand crank, but I've never seen one of those in a real machine shop, and never felt the need myself. I think they were useful in the olden days when economy lathes didn't have backgears.

Finally, if you don't have a resettable dial, and my ML7 didn't, advance the cross slide till it scrapes the job, then set the top slide to half the cross slide value, then add 20 thou to cross slide and 10 thou to topslide and take the first cut. The topslide keeps a running record of where you are up to.

[mark costello 1Participant @markcostello1]

If anyone thinks there is more ways to skin a cat……..Has Anyone tried cutting an internal thread and having the cross slide angled to the right like this " / "and cutting threads on the front side ? It makes the stick out of the boring bar absolutely minimal and the dial reads correctly. Been doing it that way for a coon ages.

[Author]

Posts