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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: Screwcutting on the lathe
17/11/2019 20:27:36
Posted by Frances IoM on 17/11/2019 20:23:37:
M18 x 1.5mm is a fairly common thread - taps + dies should be available - easy to find such advertised

It's exceedingly common being the thread for spark plugs, glow plugs and lambda sensors on a wide range of vehicles.

Thread: Rod Stewart's Model Railway
15/11/2019 01:17:13
Posted by Andrew Evans on 14/11/2019 08:25:03:

First Cut Is The Deepest was actually a reference to Rod's experience using a lathe.

He must have been turning a thread....

Thread: 1.75". Chuck backplate.
13/11/2019 12:34:05

If you want to make a Raglan backplate/faceplate by re-purposing one from another lathe you'll need to find on with a sufficiently wide boss yet an existing thread of 1.5" or less to allow enough material to cut the 6tpi square thread.

A Boxford one would suffice, if the rear boss is wide enough to accommodate the Raglan thread.

Thread: What would you call this tool
12/11/2019 08:27:36

That's a powered work head for a tool and cutter grinder. It'll fetch good money if you put it up for sale.

Thread: Suitable metal / enclosure for project
11/11/2019 00:29:35

If I can suggest - the motor on my 180mm diamond lapping machine is tiny, about 60mm cubed, and that uses disk far larger than you plan for your 50mm graver sharpener. It has a belt drive reduction for the large discs to get about 400rpm

Why not look into building a battery-powered machine perhaps using 18660 batteries and a geared DC motor with the disc mounted on a backing plate directly on the output shaft? All you'd need then is a small switch and charging port and mount it all into a plastic enclosure.

Thread: machine dovetails.
10/11/2019 18:20:40
Posted by old mart on 10/11/2019 17:20:07:

Its the narrower gap that would need machining, the other one incorporates a tapered jib. The minimum diameter of cutter which would cut the entire dovetail is 35mm, and that size would cut about 2/3 of the wall thickness of the bosses off. Yesterday, we removed the cross slide and I relieved the centre portion of the dovetail with a file. The area which was filed allowed for a minimum of 1 1/2" bearing surface remaining at each end at maximum travel of the X axis. The travel is asymmetric, being slightly further to the right than to the left, actually leaving about 4 1/2" at the left end, and 3 1/2" at the right, so something like 6" was relieved.

The mill was re assembled, but we did not have time to find out if there was any improvement. Next Wednesday we will know.

I wonder how Senior cut the dovetail in the first place?

Edited By old mart on 10/11/2019 17:23:13

It was probably originally planed and then ground or scraped.

The wear is quite apparent on the face in view which is concentrated around the ends as you would expect. This will have the effect of 'loosening' the table at the travel extents in the way you describe and coupled to the inevitable wear on the angled vee ways will make the table rock the way it is.

The thing is you cannot fix that by just machining the one vee. You need to machine/grind and/or scrape the top flat AND parallel with the y-axis flat way first and then map the wear in the front and rear vee then figure out where it needs machining/scraping. If you just go at it you'll have no idea if the x travel is going to be perfectly perpendicular to the Y travel both horizontally and vertically.

Thread: Tools for Super 7
07/11/2019 12:06:34
Posted by Phil P on 06/11/2019 23:11:29:

I use a piece of 1/4" square "Stellite" in my tangential tool holder, I always sharpen it on the side of the wheel so I get a flat cutting face and then keep a really keen edge with an occasional touch up with one of those cheap diamond hand file thingy's.

Unless I need a specific shaped form tool for something, this is my "Go To" tool every time now. The surface finish it produces is superb. The Stellite tends to keep a sharp edge for much longer than regular HSS tool steel.


Stellite particularly has a 'favourite' orientation. If you look at a new piece it will have a small notch ground on one edge at the end. This should be the upper edge when being used conventionally as it's the strongest orientation.

Doesn't affect your tangential use just a FYI.

Thread: Inverters and stop switches
07/11/2019 11:27:03

At work we have numerous items of high-powered portable/pedestrian operated plant, probably a couple of hundred different machines from 1kw to 35kw nearly all 'high risk'. Many of them have three Estops but not one single one of them is fitted with an Estop that disconnects the incoming supply. All of them stop the motor and serve as a control interlock so that no control can be used until the Estop is released.

BTW I wasn't suggesting than someone SHOULD power a VFD with a NVR. It was just a suggestion for someone who was so paranoid about the above that they find it a distraction. I wouldn't find it necessary myself, at all.

06/11/2019 20:35:49

An Estop you wire into the control circuit, otherwise it's not and Estop it's a power disconnect, and not even a good one as it'll invariably leave neutral connected. if you desperately want the VFD to be instantly disconnect-able then feed it via a NVR.

Stopping in an emergency you want maximum braking and you won't get that by killing the VFD power.

Thread: building a myford super 7 from bits ?
05/11/2019 17:47:09

If the bed is straight and flat then the only thing that matters really is the headstock and tailstock centres are the same height. The underside of the headstock won't wear so it should be as aligned to the spindle as when it was new.

05/11/2019 12:47:09

You can chop & change most parts at will. My friend bought seven rusty machines and is renovating them all one at a time.

Thread: What kind of diamond wheel i/ lap would the forum recommended?
05/11/2019 12:07:45

I use the lap wheels at 400rpm for sharpening carbide scrapers. You could probably go up a bit in speed for a 50mm wheel. Use some kind of solvent to cool/clean the disk as you use it.

Thread: Reaming - depth of cut
05/11/2019 11:50:20
Posted by Steve Sedgall 1 on 05/11/2019 09:15:05:

Just to add to the confusion the more material the reamer has to remove the bigger the reamed hole will be. Also the speed of the reamer/work will have an effect on overall size. Fast surface speeds will produce a hole bigger than slower speeds. As my old mentor used to say if you have a surface finish/size issue then check your roughing tool first.

An important fact that has caught me out more than once. If you cut so much that the chips pack the flute of the reamer, the hole is going to be over-size. I've even caused a reamer to cut over-size deliberately by packing one flute with blue paper towel. Turned a tight fit into a free-sliding fit.

Thread: How was this recording done?
04/11/2019 00:16:52

It says in the description right under the video:

Recorded with

Edited By Pete Rimmer on 04/11/2019 00:17:45

Thread: Pratt Burnerd 4 jaw Chuck jaw alignment
24/10/2019 11:20:36

I just checked, my spare jaws are PB but they are for a smaller 4-jaw having a .200 slot and 8tpi screws. The jaws in my 8" 4-jaws and a bit bigger with coarser screws.

23/10/2019 11:41:07

You should be able to grind an essentially brand new chuck without fear of the jaws cocking. If they do cock then they wouldn't be able to clamp anything effectively inside and outside without suffering problems.

22/10/2019 14:00:46

If you're going to grind then then turn a ring concentric on OD and ID and clamp it in the jaws on the ring's ID. Clock the ring in the 4 locations directly over each jaw and adjust until all read the same then you can grind them very gently at slow rpm.

Use the biggest grinding wheel you can sensibly fit in the hole so that when you dress it true you get the maximum amount of grinding before the wear on the grinding wheel reaches full span. You might do well to make a roughing pass, dress the wheel then take a very light finishing pass.

22/10/2019 00:43:31

I have I think 3 sets of 4-jaw chuck jaws of unknown provenance. Put up some basic dims of your jaws and I'll check the ones I have. In the unlikely event that one of those set match, you can have it.

20/10/2019 23:03:21

I think it's doubtful that it's the jaws themselves at fault. Is this one of those lightweight 4-jaw chucks with a shallow section and pockets cast in the back? They bend quite easily if you go daft with the chuck key. I would sweep the chuck face and then the jaw guides with a dial gauge mag-mounted to the cross slide. If the face of the chuck is dished then you can grind the jaws but they might not then be straight at another diameter.

Thread: Slideways oil
20/10/2019 16:05:49

Slideway oil here. Seems folly to use anything else unless I had none. Motor oil is better than nothing but slideway oil is made to maintain it's film under the flat ways without squeezing out, whereas motor oil is designed primarily to be pumped under pressure into tight gaps then run out so more oil can follow..

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