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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: 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.

16/04/2020 18:33:12
Posted by mechman48 on 16/04/2020 17:17:27:

I used a couple of 12 mm HSS tool stock & a digi level to check for any twist on my lathe...

Headstock end...

lathe level check 2014 (1).jpg

Tail stock end...

lathe level check 2014 (2).jpg

along the bed... rear shear...0.1mm off...

lathe level check 2014 (4).jpg

Front shear...

lathe level check 2014 (3).jpg

Same as rear shear, obviously, 0.1mm off length wise, but no twist head stock to tail stock, good enough for me. Pay a £150 + for an engineers level for home check maybe twice a year, I think not.

I have used Eng' box levels, DTI's & electronic alignment equipment when I used to instal / realign turbines / pumps & gearboxes etc, when I was in the middle of the desert a few times but they had to be spot on, including adjustment & offsets for thermal expansion. Save your money for some useful tooling is my thought.

George.

Your level is only resolving to 6 minutes of arc - that's not even it's accuracy, but it's resolution. A typical engineer's level will measure 10 seconds of arc or better, 36 times more sensitive to a change in angle.

In real terms it means that your electronic level won't register 6 thou of twist in a bed 4" wide (approx. the length of that HSS bit). It's not sensitive enough.

Thread: Help with Maths ratio problem?
15/04/2020 21:18:00

Strictly speaking he can make 500ml of fizzy drink. 480ml of lime/lemonade mix and 20ml of straight lemonade.

Thread: Correct boring with a steady - advice please :-)
13/04/2020 23:08:02
Posted by Hopper on 13/04/2020 21:30:27:
Posted by Pete Rimmer on 13/04/2020 21:01:56:
Posted by YouraT on 13/04/2020 11:31:49:

If you have two dial gauges put one on the side and one on the top (or bottom) up near the steady rest. Release the steady fingers from the part and turn it by hand tapping it true until the dials read no runout and zero them. Now bring the steady fingers in until all three are touching and the dials read zero, the part will be running true in the steady.

If it's not round on the OD you'll have to stuff a centre in the end and turn it true first.

Using dial indicators (and why would you use two?) will only show the work is concentric. It could still be out of alignment with the lathe axis, causing a taper. Bit like using an offset tailstock centre.

Hopper read my post again more carefully. You use the dial indicators to true the part with the fingers not touching. That gets the end of the part turning on-axis with no runout. Then you zero the dials and bring the fingers in until they are all touching and the dials are both zero. That means you have it constrained by the fingers AND still on axis. It's about as accurate as you can get it, the only rotational axis error then is in whatever runout you have in the 3-jaw at the other end (and he has a grip-tru so that could be brought to zero).

Setting the finger at the chuck works most times, done it many times but you can still have the part walk out of the jaws especially on thin walled parts. If you set the fingers touching at the chuck then slide it back, your fingers will be centring the part the other end off-axis by whatever runout you have in your 3-jaw. Flat bed ways have the extra potential for error by the amount of clearance between the steady and the inside shears.

Both methods work but to different degrees of accuracy.

13/04/2020 21:01:56
Posted by YouraT on 13/04/2020 11:31:49:

Hi all.

Returning to a 'filed' project, I'm trying to bore a 60mm long hole in an aluminium bar using my lathe's power carriage feed, but I'm finding it's significantly tapered to the tune of around 0.6mm (in 25mm or so) over the 60mm length of the hole, with the end closest to the chuck being the smallest. The lathe is a Denford Viceroy 250, but I don't think that's particularly relevant for this question.

As the bar is around 150mm long, I've brought out my fixed steady to help keep things in place (see picture) but I wonder if my lack of experience in using it is causing the taper I'm seeing.

I've simply used the steady on the outside of the bar (which is perhaps not perfectly round....?) and gone from there - is there a technique/order of setup things up that I should be using in order to ensure everything is lined up properly to give me a non-tapered bore?

The boring bar is of course sticking out quite a long way, but I'm taking deliberately light cuts and in any case, the deflection forces on the bar should be the same at all points along the cut.

Thanks,

Youra.20200413_104615.jpg

If you have two dial gauges put one on the side and one on the top (or bottom) up near the steady rest. Release the steady fingers from the part and turn it by hand tapping it true until the dials read no runout and zero them. Now bring the steady fingers in until all three are touching and the dials read zero, the part will be running true in the steady.

If it's not round on the OD you'll have to stuff a centre in the end and turn it true first.

TBH that boring bar is too thin for that much stick-out. It might well be deflecting as you feed it in under load.

Thread: Glass scale /DRO compatibility
13/04/2020 12:08:10

TTL = transistor-transistor logic signal, for simplification purposes it just means square wave.

The unit you have is pretty much the common standard for budget scales and head units so any of the regular scales you'll find should fit it. You'd have a more difficult time finding new scales that didn't.

See if you can find the manual for the head unit because you might want to change the scale resolution setting. If you can't you better get a scale with the same resolution as the one you already have so that it reads correctly.

Pete.

Thread: An Easter Tale of Cordless Batteries.
12/04/2020 13:54:05

I had this problem with a dead Dewalt 14.4v screw gun. The battery was so flat that the charger would not detect that there was a battery connected. My solution was to very briefly connect a 12v motorbike battery across the terminals. As soon as I did that the battery charged up just fine and has been working this past 18 months.

Thread: Large Crane
04/04/2020 23:49:34

A job I did we used a 425tonnes capacity Sheerleg "Norma" out of Zebrugge to lift up to 400 tonnes on the river Medway. The Norma has since been scrapped but I bet that ship in the pic above could have picked her out of the water :D

Thread: Sourcing gunmetal for leadscrew nuts.
31/03/2020 07:45:27
Posted by Hopper on 31/03/2020 02:35:53:

Havent seen gunmetal advertised in years. When was the last time guns were made from yellow metal? LG2 bronze seems to be the modern equivalent. It contains tin, lead, zinc, nickel and iron if it is made to full spec -- but probably varies depending on manufacturer.

But if you want bronze go with LG2.

LG2 = Leaded Gunmetal

Thread: New DTI "Glass"
30/03/2020 18:26:45

An Etalon dial gauge is definitely worthy of repair.

I would make a new crystal from a welding mask lens cover. You can pick the screen covers up for peanuts as they are disposable and you'll get a few tries at it.

 

Edited By Pete Rimmer on 30/03/2020 18:27:32

Thread: Square thread cutting
30/03/2020 15:29:57

Nice one George, that has come out much better. I don;t know how they do it but they do it well!

Now, if you get really bored in your isolation and fancy doing the whole manual, send it to me and I'll make a very nice PDF for you.

Pete.

30/03/2020 14:18:22

George, I cleaned up your photo a bit. Not the best result but it's a bit easier if you ever want to print it out.

It would be nice to get a pic of the whole page if you could. If you took the pic with your smartphone there's a great app called CaMScanner that will automatically clean up photos to make them much more readable.

Pete.

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