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Member postings for Pete Rimmer

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

Thread: Removing bang in self tappers
27/09/2020 17:39:10

They are called drive screws. I usually lift them by carefully tapping old feeler gauges under the plate they are holding down. Go slowly and you can raise the drive screw enough to get side cutters under the head.

Thread: Spindle Speed
25/09/2020 19:09:40

Many good lathes fitted with variable speed have also been fitted with a tacho or speed readout.

Rivett 1020, Smart & Brown 1024, Holbrook minor, Monarch 10EE - all top-bracket machines. If those manufacturers saw fit to fit them then it's perfectly reasonable for a machine being retro-fitted with variable speed to also have one fitted.

Thread: Making a pinion with a fly cutter
20/09/2020 12:03:41

You can still make cutters from carbon steel. Just buy a large rusty twist drill with a MT shank and make cutters from that. The larger MT shanks should yield a good number of small cutters for pennies outlay. Harden them yourself.

Thread: scraping technique
18/09/2020 10:33:36

Few good reasons to do it the other way IMO. Scraping tapered gibs in-place for contact perhaps.

Thread: Best way to remember Mill movements when turning hand wheels
18/09/2020 07:01:12

FWIW my mill has a RH screw for the X (which moves with the table) and LH for the Y (which does not), so turning the handle always moves the part the same way a bolt would screw in and out if you were turning a bolt instead of a handle. I suspect that the majority of milling machines will be the same.

17/09/2020 14:44:32
Posted by Michael Gilligan on 17/09/2020 08:09:56:
Posted by Dave S on 17/09/2020 07:55:43:

.
It becomes second nature after a period.

[…]

.

This reminds me of a ‘classic’ problem in Ergonomics ...

I forget the exact details of the disaster, but basically a ship was in trouble and a drain-cock needed to be urgently closed ... but the seaman reverted to instinct, and ‘turned it down’ as one would with an amplifier knob.

MichaelG.

Edited By Michael Gilligan on 17/09/2020 08:12:04

I guess that guy never washed his hands after using the loo, because natural instinct for a water tap is to turn it off clockwise.

Thread: scraping technique
17/09/2020 12:37:19

If you blue the part you have to clean and blue it every time. Blue the plate all you have to do is clean the part every time, and run the roller over the plate to re-distribute the blue.

Also, if you blue the plate you rub the part gently to transfer the blue onto the touching points. the part should not touch the plate, only the blue. If you blue the part you're then using the plate to scrape blue off the high spots. Unnecessary wear on the expensive plate.

Thread: Eagle 3 Surface Grinder - Moving Query
15/09/2020 18:46:41

Looks fair enough on the surface. The spindle nut sets the bearing pre-load on these so don't ever run it without the nut done up.

Looking forward to seeing how it comes out.

Thread: Facing parallel between centres.
14/09/2020 19:08:36
Posted by Graham Meek on 14/09/2020 11:28:54:

"Facing parallel between centres" is the title of this post. Failure to get a good result is hardly a claim that "it does not work". Especially if the methodology of this process is not fully understood.

I do wonder how much of the of the aversion to this "between centres process", is based on disturbing the tailstock setting. It has always been a big No, No, with some individuals. The same is true when it comes to moving the topslide, when anyone advocates the set over top-slide method of Screwcutting.

Those who know their machine tool history, will know, " Dead Centres" were the basis of all turned work at one time. It was not until later on that the "Live Mandrel" was developed and the faceplate became available. Dead Centres are still used in cylindrical grinding, for most work. The lathe Mandrel on the lathe in the picture above was no doubt finished this way.

Regards

Gray,

Well said Graham. Moving-jaw chucks were an accessory at one time. Lathes would be supplied with centres and drive dogs.

One should be able to produce exceptionally good parallelism working between centres.

Thread: Eagle 3 Surface Grinder - Moving Query
14/09/2020 18:59:26

Let's have some photos of it then!

Remember, the table is lubricated with 10 weight oil, not regular way oil.

Thread: Use of 2 front wheeled motorcycles on the TdeF
13/09/2020 20:50:57

I've no idea about the TDF but those 2-front-wheel bikes are popular in the UK because our licensing laws allows for(some of) them to be ridden on a car license whilst remaining in the motorcycle taxation class, so they can (in London, anyway) be ridden in most bus lanes, are exempt from congestion charge and use motorcycle parking bays most of which are free.

It's all down to how far apart the wheels are. Some manufacturers do a UK-specific model to exploit the 'loophole'.

Thread: ECLIPSE MAGNETIC CHUCK
13/09/2020 16:26:47

Gary, just like some permanent magnet motors need re-magnetising after disassembly, the flux path needs keeping constantly for the magnets to not lose some effort. The design of the Eclipse chucks causes the on-off lever to divert the flux path rather than break the flux path completely.

It's all explained on page 12 of the manual I linked to, which has images showing how the control lever slides the magnets in and out of phase with the top plate to turn the chuck on and off.

Edited By Pete Rimmer on 13/09/2020 16:29:41

Thread: Adjuster mechanism
13/09/2020 12:17:50

Put a small bush in the ally plate to prevent the hole wearing and capture the rod end with locknuts and thrust washers. If you wanted to get really posh use 6mm ID thrust bearings and nylocks or locknuts.

A lot depends on if the moving part slides or hinges. If it hinges they you'll have to allow for the rod to swing a bit unless the range of movement is very small.

Thread: ECLIPSE MAGNETIC CHUCK
13/09/2020 12:00:17
Posted by Oldiron on 13/09/2020 11:37:34:
Posted by Gary Wooding on 13/09/2020 10:31:03:

I'm going to show my ignorance here, but I don't understand why it would it lose it's magnetism just by dismantling it. The old-fashioned horseshoe magnets I had at school all those years ago had keepers, but they certainly didn't lose their magnetism if you removed the keeper for a few hours. What am I missing?

Nor me Gary. Seems to be plenty of YT videos showing the process for different makes. What makes the Eclipse so different from all the others ?

regards

The difference is that those youtubers sole interest is in showing off their 'skills' whereas Eclipse produced their handbook as technical information about their products for their end-users. They don't state that the magnetism will be lost, but reduced. How is youtube-guy going to quantify that reduction, and why would they, if they could? It would be just inviting adverse comments about 'ruining' the chuck.

I guess if your chuck is so seized up that it's completely unusable then you have nothing to lose by making it work again, to whatever extent. Reduced workholding is better than no workholding at all and you can always add blocking or moderate your cuts. Just don't go stripping it down unnecessarily on the strength of youtube recommendations.

Thread: Facing parallel between centres.
13/09/2020 11:50:00
Posted by Hopper on 13/09/2020 11:47:59:

LOL. Yes you missed the previous two or three threads on this job. He got it within half a thou across 4 inches but now wants to get to better than that if possible, You'd be lucky to get better on most mills or hobby lathes IMHO. Baz is right where he says above that grinding is the solution for precision of sub-thou increments.

I'd scrape that part parallel in no time.

13/09/2020 11:48:32

Ok a quick calculation. Let's suppose that Robin's part WAS turned between centres and has 1.5 thou taper over 4" - that's 8 tenths off-set for the centres. That would put the end faces off-square by 0.011 degrees, or, nothing in the real world.

If you faced the 6" diameter part and didn't relieve the centre you'll have just over half a thou convex or concavity on the end (actually 0.00052" over the full face but if you relieved the middle 4" of that 6" face to leave a 1" annular land that 'concavity' is reduced to 0.00013" over the width of the land. In other words it will blue up almost perfectly.

Who would argue that a face isn't flat when it blues up on a surface plate?

13/09/2020 11:14:18
Posted by Hopper on 13/09/2020 09:51:00:
Posted by Pete Rimmer on 13/09/2020 08:44:36:

The faces will not be parallel but the ends of the part will be co-planar which is the desired result.

Both faces will be convex. Call it what you like. Try perching your mill column on top of a disc with convex faces top and bottom and see if it acts like a ball joint or not.

I missed this reply previously.

Firstly, the faces might be square, or convex, or concave but convex is not guaranteed. That depends on which was your setup is biased.

For a riser you would not machine the whole face flat but a bearing face on the periphery with the centre relieved - just like any quality cylindrical square. To do otherwise would be inviting trouble from dings, burrs or trapped debris on the face - including any 'convex' issues - during assembly or at any time in the future. These are all negated with a relieved centre section and if you do it, any tiny amount of cone on the end faces (and it will be tiny) is irrelevant for the application.

What is most difficult is figuring out where Robin is measuring his discrepancy. He states "about a thou and a half on 4" diameter". I suspect he means 'over 4" length' but if it's diameter he's measuring it's not really relevant except to identify that his centres need adjusting by 7-8 tenths.

13/09/2020 10:24:03

Robin says he is using a drive pin. Presumably this is drilled into the face. If that is the case he should have access to both ends in the same setup. You can't beat that. The rotation of the part on axis is the most critical aspect. I don't see the relevance of tool changing or saddle location.

Thread: ECLIPSE MAGNETIC CHUCK
13/09/2020 09:29:31

Absolutely don't dismantle an Eclipse chuck, it will lose it's magnetism. There is no need to do anything in particular to preserve the magnetism (such as using a keeper or storing it switched on or off) except to never dismantle it.

I have somewhere a more informative Eclipse manual that someone kindly sent me as a collection of photographed pages. I will see if I can clean them up and present them in a PDF. It includes lubrication info.

EDIT: Here you go. I cleaned it up on my mobile phone using Camscanner app and put it in my dropbox.

Eclipse Permanent Magnet Chuck Users Handbook

Pete.

Edited By Pete Rimmer on 13/09/2020 09:47:02

Thread: Facing parallel between centres.
13/09/2020 08:44:36
Posted by Hopper on 13/09/2020 08:29:32:

No. The ends will be conical if you cut straight in square to the lathe axis while the job axis is at an angle to the lathe axis. The ends in the illustration are parallel, but they were turned BEFORE the tailstock was offset in this taper turning example. If you now face the tailstock end of the job, it will be a convex cone. If you then flip the job end for end and face the other end, it too will be convex. Two convex surfaces are never going to be parallel.

Edited By Hopper on 13/09/2020 08:32:48

The faces will not be parallel but the ends of the part will be co-planar which is the desired result.

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