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Member postings for ega

Here is a list of all the postings ega has made in our forums. Click on a thread name to jump to the thread.

Thread: Toolholders & Inserts
15/11/2018 11:12:26

I shall continue to pray for an effective spell checker - not that it would have saved this typo.

Thread: Warco WM250 Colle set question 2
15/11/2018 11:09:37

Posted by JasonB on 15/11/2018 07:11:38:

...

5C will hold short work down to 1mm long

5C backstop available for batch work.

Thanks for your 5C/ER comparison.

There is an obvious temptation to grip work shorter than the collet in an ER chuck and I wonder how far this can safely be taken? Certainly not 1mm, but have you a helpful rule of thumb?

There is, of course, no reason why a backstop cannot be contrived for use with an ER chuck.

Thread: Do I need a hole in sintered bronze bearings
14/11/2018 17:13:48

Posted by Michael Gilligan on 13/11/2018 22:34:51:

...

Picador had the right idea, with their Plummer Blocks:

I was intrigued to see from your patent link that the Germanic-sounding Herbert Kohn Staub was a British subject. Picador were major players in the early days of my interest in machines and it is a shame that they seem no longer to function.

Thread: Deburing holes
12/11/2018 10:31:53

Thanks for the noga link.

I see that the reversible tool is not only recommended for diametral holes in pipe but will deburr the other side of the hole, too!

Thread: Er32 chuck for Fortis lathe
11/11/2018 16:35:14
Posted by Clive Brown 1 on 11/11/2018 14:31:53:

Don't necessarily put the run-out down to your "cheapo" collets. I made a similar ER25 chuck and at first had a few thou. run-out, similar for all my collets despite the taper running true. I thought that this might be due to making the screw-thread a wee bit too tight, so took off a shaving. Sure enough, the run-out reduced to less than a thou. at which I'm quite happy.

Interesting point; my Quick Step Mill with ER20 spindle came with a rather loose collet nut. The designer/manufacturer may have had the same idea in mind.

11/11/2018 14:28:01
Posted by sean logie on 11/11/2018 14:00:04:
My old Fortis is a bit rough around the edges but it's accurate enough for me 😉

Sean

Tony Griffiths gives them a good write-up as you are no doubt aware.

Thread: Myford ml7 tools size
11/11/2018 14:24:42
Posted by Mark Rand on 11/11/2018 00:02:47:

I had a four way tool post on the first ML7 I got. On that one and, later dad's long bed ML7B that I inherited, I didn't use it. I found that 12mm tools with dedicated shims directly on the top slide table were as quick and more flexible than the four way tool post.

The OP doesn't say what tool holding facility he has but I can't help feeling that for most purposes almost anything would be better than the standard sprung clogheel arrangement.

Thread: Er32 chuck for Fortis lathe
11/11/2018 13:55:03

sean logie:

For 'tis a jolly good lathe!

Here is my shop-made version showing also a GHT-inspired dividing attachment for use with milling and drilling spindle:

dscn1447.jpg

Not obvious in the photo but I have made the chuck body long enough to be able to work up close despite the gap.

Thread: An alternative to parting-off
08/11/2018 14:05:15
Posted by Oldiron on 04/11/2018 12:54:43:

Here is an interesting webpage for those interested.

**LINK**

Thanks, Oldiron, for these tips from the horse's mouth; it is indeed interesting to compare them with opinions on the thread (always remembering that the author is concerned with industrial applications).

Thread: Small Hex Fastenings
07/11/2018 17:48:48
Posted by Howard Lewis on 06/11/2018 16:55:23

...

During WW2, to save material, Whitworth and BSF hexagons were changed to the next size down, so a 5/16 BSF spanner then operated on a 3/8 BSW fixing, and so on.

Can anyone confirm my faint impression that this development had started pre-WW2?

I seem to remember that my 1931 Austin Seven had fastenings with the reduced size hexagons and that this caused me some confusion when buying my first spanners.

Thread: An alternative to parting-off
07/11/2018 17:35:32
Posted by Mark Rand on 07/11/2018 15:45:34:
Posted by ega on 07/11/2018 13:52:59:

If I read you correctly, you would recommend that the rear mounted carbide tool be set below centre?

Can you elaborate on "cope badly"?

Yes, if the tool were rear mounted, it'd want to be physically below centre.

If the work rides over the cutting edge of the insert as the tool gets to the centre of the job, due to flexibility in either work or tool holding, then it puts the cutting edge of the tool in tension rather than compression. It just peels the front off the tool before you can do anything about it.

If the cutting edge is fractionally above centre, it's harder for this to happen and the insert will happily push through the last little bit of stock so long as it's in compression.

Having the tool below centre will cost you an insert per cut surprise.

Edited By Mark Rand on 07/11/2018 15:46:35

Thank you for this cogent explanation. I am going to check the height of my parting tool which is of the tangentially-clamped variety. The makers, ISCAR, claim that the design "Provides a solution to the problem of inserts being pulled out during retraction"; this is not the "diving" effect you have described but the tangential tool does seem to be better able to resist it.

07/11/2018 13:52:59
Posted by Mark Rand on 07/11/2018 12:58:46:

The major advantage of the insert parting tools is that the hollowed top folds the chip in to a U shape, so that it is narrower than the slot the tool is cutting. That makes chip ejection far more effective and reduces the jamming that a flat topped HSS tool is prone to. G.H.Thomas recommended that the HSS tools have a groove ground on the top face to achieve the same result.

The carbide tools really cope badly with the tool climbing under the work or the work climbing over the tool, so it's normal practice to tun them just a few thou above centre height.

If I read you correctly, you would recommend that the rear mounted carbide tool be set below centre?

Can you elaborate on "cope badly"?

Good point about the GHT groove.

07/11/2018 12:02:47

I use an inserted carbide tip parting off tool on my 1960s Willson slant bed whose top speed is 954 rpm, typically parting off at up to half that speed.

I think that speed is only one factor; the topic has been well canvassed here, of course.

Unfortunately, in my experience the pricier tipped tools work better than the budget ones.

Thread: RF 31 BENCH MILL DRILL
06/11/2018 12:06:04
Posted by Mike Poole on 06/11/2018 09:35:32:

... If you have already got MT 3 tooling it may be cheaper and easier to replace it with R8 tooling rather than change the spindle....

Mike

And you could get a fair price for the unwanted MT3 tooling by advertising here.

Thread: Deburing holes
04/11/2018 23:51:12
Posted by Nick Hulme on 04/11/2018 18:59:34:
Posted by ega on 18/10/2018 14:06:29:

I had occasion to cut the tip off a step drill and afterwards it occurred to me that, mounted in a suitable handle, it would make an effective countersink/deburring tool:

...

It works best, of course, when the preceding step is a good fit in the hole being deburred.

On the tricky question of deburring holes in tubes, I suppose a CNC machine could do the job; I just make do with a small half round scraper.

Thanks!

I'm stealing that idea!

Feel free!

Mine uses a metric drill that rises by twos but a more versatile tool would be in steps of one millimetre. Again, if you didn't want to tie up the step drill permanently it could be held in a chuck handle.

Thread: An alternative to parting-off
04/11/2018 11:33:27
Posted by vintage engineer on 04/11/2018 09:41:17:

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

Where does one obtain a parting off tool with a 5" projection? And what lathe runs it?

Not everybody has power cross feed. CNC apart, how does conventional parting off account for the progressive reduction in surface speed of the cut?

Thread: material
03/11/2018 14:19:27

ajl langley:

I assume you have tried Castorama?

Reading your post made me think of the sorely-missed K R Whiston; his "cat" listed very much the kind of thing you are after.

Thread: Beautiful QCTP
03/11/2018 11:30:47

blowlamp:

Well, he certainly looks as though he is about to do a "quick change"

jimmy b:

Thanks for Aloris link

Thread: new member in france
02/11/2018 23:47:44

There was a contributor with a French name, Yves Rayssiguier: see MEWs 27 and 50. He seems not to be a member although there are three other Yves.

Thread: Beautiful QCTP
02/11/2018 23:37:57

I assumed "Adonis" was a typo for Aloris.

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