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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: Eagle Surface grinder - who here uses one?
03/05/2020 08:19:27

Thanks Steve and Jeff

Jeff the spindle itself was fine, they are hardened. The bearings were shot though and the only exact-size angular contacts I could find were wheel bearings for old British cars so I turned a couple of sleeves and fitted modern metric angular contacts. The floating bearing on the rear was a standard 1"x2.5"x0.75" ball bearing and I did find replacements for that. The spindle also had a through-hole near the front so I made a spring-loaded plunger to act as a spindle lock for putting a spanner on the wheel nut.

02/05/2020 23:50:17

Quick follow-up here. I found that regular slideway oil wouldn't flow properly along the delivery channel to feed the ways. I put some in both ends of the table and although some made it along, most was still sitting in the feed channel weeks later. So I've taken to using 10 weight oil (the equivalent of the specified Magna ZA) and it keeps the slideways nicely oiled.

Anyway, I finished rebuilding it this weekend so here's a couple of before and after pics. A lot of work went into this machine - not just a clean and paint. All of the ways are scraped, new poly vee belt with new pulleys made. New metric spindle bearings and of course a good clean and paint.

Before, part-stripped for transport:

And now in it's finished state:

Thread: Dead centre vs. live centre
02/05/2020 11:33:12

A live centre turns with the spindle, a dead centre does not. A revolving centre is neither live nor dead in the traditional sense but in recent times the commonly-used definition seems to have changed to make revolving centres 'live' and solid ones 'dead'.

Anyway, the advantage of a dead centre in the tailstock is that it allows for a slightly longer workpiece if you're approaching your limit in bed length, and will hold the work more concentric all but the best quality revolving centres. Disadvantage is that it must be lubed and you're limited to about 300rpm then you risk burning up the tip. Carbide-tipped ones will suffer a bit more abuse without destroying the tip.

Thread: Warco WM16 Gib strips
02/05/2020 07:47:39

Be warned that if you hit the end of the gib use a block of aluminium. Even the slightest ding or burr on the gib will render it useless for proper adjustment.

Thread: Gear Cutting
01/05/2020 22:40:53

It's no wonder you had rough meshing on your back gear because the spindle and back gear shaft are at fixed centres. If you're meshing gears on the screwcutting banjo you should be able to adjust the centres for smoother meshing. It's not ideal but it's a lot more ideal than trying to mesh gears of two different pitches and very much do-able.

01/05/2020 18:37:04

If you had to choose between meshing a 14.5pa gear with a 20pa gear of the same DP, and meshing a 18dp gear with a 20.319dp gear (equal to 1.25MOD) then you'd go for the PA mis-match every time.

Thread: Measuring wear on a surface grinder
25/04/2020 15:01:56
Posted by Dave S on 25/04/2020 12:54:08:

Crosswise on the 6” parallel is less clear.

Might be a ramp of about 6-8 tenths, but sometimes it appears to be a dip of 3-4 tenths, but not consistently and not at the same point in the travel.

Dave

It's a sign of wear in the slide. I'll try to do a sketch to explain it.

EDIT: I don't have to - I found an old pic of the wear on mine.

As you can see the ways wear low at both ends and this causes the cross table to travel in an arc instead of a straight line. When you put the parallel on the chuck it IS straight, so making it travel in an arc with the table will give a high reading at both ends. The reason you're getting different reading in both directions is probably because the table is rocking ever so slightly away from the direction of travel.

As you can see - mine was badly worn, much more than your indicated figures.

Edited By Pete Rimmer on 25/04/2020 15:12:20

25/04/2020 11:55:22

If the cross table ways are worn and you grind the chuck you'll be grinding the chuck convex. If someone hasn't already done it.

24/04/2020 19:01:19

It's very possible to have the machine so worn that it produces 'bent' parts and grinding the chuck will not fix that nor will the popular test of putting blocks on the corners of the chuck and grinding them to compare the thicknesses.

I had one of these and the cross axis ways were so worn that anything I ground was convex in the short axis. i did set about re-scraping it but after a lot of work lost heart and got rid of it, mostly because I didn't have a straight edge to fit the cross table ways (you can't fit a regular straight edge in there) and because the wear so so bad that the cross slide screw and nut were trying to carry the weight of the cross slide and table.

You can use your test to check for 'banana ways' but orientate the straight edge across the chuck and check that axis. If the ways are straight it will either indicated evenly along the length or have a gradual rise or fall on the dial. If they are as badly worn as mine the indicator will fall then rise showing a low reading in the middle.

 

Edited By Pete Rimmer on 24/04/2020 19:08:17

Thread: J&S 540 way lube question
23/04/2020 08:17:47

Early 640's (the ones with the straight-sided column and belt drive pump) were manually lubed saddle ways. Often neglected. The early ones also had small brass flow control valves behind the table for the pumped oil.

Thread: Delay in dispatch and delivery
20/04/2020 19:06:25

They are probably back-logged in the system. I was in the butchers this weekend and there was a postman queueing outside the door. I overheard him saying that there were 200,000 parcels stuck at the Medway distribution centre. He said it was far busier there than it had ever been any Christmas he could remember, but they had only a fraction of the staff.

Thread: What is this small hobbing cutter for?
18/04/2020 23:38:34

Clock escapement/ ratchet wheel. I've got a bunch of them. That one is in pretty sad condition.

Thread: Enamel Paint
18/04/2020 23:31:52
Posted by JasonB on 18/04/2020 16:16:24:

What are you thinning it with?

24hrs can be a bit too long, i've used a couple of paints that state recoat within a few hours but once past 24 you need to leave it several weeks before recoating.

Edited By JasonB on 18/04/2020 17:41:25

The enamel paint I use on my machines is like that. Second coat within 2 hours or leave 6 days otherwise it will trap the solvent in the first coat and could blister.

Thread: Angular contact bearing end float in face-to-face config.
18/04/2020 22:36:17

Mark, I suppose you have checked the bearing orientation? The axial line of thrust must be opposing for each one, so they must be front to front or back to back.

Thread: SPACE HEATERS
18/04/2020 22:30:33
Posted by David Jupp on 27/01/2017 13:29:53:

Heating the air in any large space will be expensive - infra red heaters (gas or electric) can be an interesting alternative. IR heats equipment/people, very little direct heating of the air. They were used in a large, draughty warehouse cum loading bay at a factory where I used to work.

I know it's an old thread but I agree with this as a consideration.I heat my workshop with a single 2kw infra-red heater and it's 215 sq/ft so three of those or a pair of 3kw should keep the OP's work space comfortable to work in, depending on height and insulation. I have a second one but two running make the place uncomfortably warm, I only use the second if I want to do a bit of painting on a large item.

Thread: Angular contact bearing end float in face-to-face config.
18/04/2020 18:21:33

Shimming is your only choice if you want to keep the bearings. I just had to do this to diagnose worn out bearings on my surface grinder.

Measure the end-float with a dial gauge then get some shim stock sandwiched between two pieces of scrap. Drill it through then turn the outside then you'll have the correct annular shim. You can do ID or OD depending on how you orientate the bearings.

Thread: Did Stuarts marking blue really do that?
18/04/2020 10:15:07

The difference ,might be something as simple as the swarf not flowing off the tip smoothly. As most of us have no doubt experienced, even a tiny change in lube - a misting of wd40 or cutting oil etc - can have a huge effect on surface finish. A 3 thou cut will produce a very fine swarf and it could be nothing more than the blue causing the swarf to roll into a bunch rather than flow away from the tip.

I was cutting some 8.5 degree included-angle tapers last week and I had to experiment a bit do avoid the swarf rolling over and marring the finish. Once I got the speeds & feed right they came out very nice.

18/04/2020 07:00:54

It's possible that it has an effect. When scraping something that is heavily blued you can get a build-up of blue + scraping dust that makes the scraper skid, especially if it's dried out a bit. It doesn't happen often but it does happen.

Thread: Scraping and Shimming Myford Headstock Bearings
17/04/2020 17:35:03

Jan Sverre's videos are always worth watching. He isn't in it for 'likes' 'subs' or money, he just enjoys sharing his knowledge and helping people.

Thread: Selecting an Engineer's level
17/04/2020 17:03:18
I was trying to keep out of this, Martin ... but I do feel the need to re-state my understanding of the semantics:

Levelling in this context [as in surveying] is the process of using a level to compare heights.

... The ambiguity comes from the assumption that it must mean setting something horizontal.

MichaelG.

Quite right Michael. Add that to the fact that the most expedient way to to check for twist is the ensure that the ways are actually level both ends. They need not be and it might not even be possible, but why complicate things?

The Colchester alignment check sheet calls it a 'transverse bed level' measurement. Seems like a pretty intuitive description.

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