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Member postings for Dave S

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

Thread: Lathe run out
12/05/2021 20:41:21

Whilst maybe not strictly correct placing it across both prismatic ways at both ends is at least consistent.

I think you can (initially anyway) assume the prismatic ways relationships do not alter along the bed - it there would be all sorts of fun with the tailstock/saddle relationship.

That implies that the reading should be the same at each end assuming the lathe is not twisted.
The photos show 2 quite different readings, so there is at least a bit of twist to look at.

Dave

11/05/2021 07:47:01

Re reading my post it isn’t clear that the 50 thou of shim was on the floor, under one of the tailstock end feet.

I wouldn’t touch the headstock until proven that it needs it. Then again it’s your machine. I recently took the spindle on my surface grinder to pieces to reset the end play, even tho the “internet” said don’t do it, that’s never a problem and your poor surface is caused by “xyz”

However I did all the tests and measurements to be certain that was the issue and went ahead and fixed it.

Now grinds beautifully.

Do the legwork first and eliminate the obvious things.

Dave

10/05/2021 20:12:52

Do you have a trusted dead centre?
I am assuming, as it looks like a fairly new lathe that bed wear can be ignored.

Chuck a short piece of scrapbinium ( something like 10mm diameter or so with 1 diameter stick out) and turn a point on it. Move the tailstock up.

compare points. They should line up exactly in both planes. Trapping a 6” ruler between them is an often mentioned way to amplify any offset, but I’ve never done that. If they match it’s fairly easy to see with a good light and some magnification (I use an optivisor).

IAssuming that the points do match you know the tailstock lines are up.
The headstock might still not be aligned with the ways, or the ways may be twisted.

I had a Harrison L5 not on a cast stand, so it stood on the headstock plinth and a 2 legged tailstock support.

IIRC it needed about 50 thou of shim to turn parallel. That was stood on a smooth level concrete floor, and L5s are not exactly “lightweight” - probably a chunk stiffer than your modern lathe.

look up the 2 collar test - and do it with a sufficiently large diameter that the bar is stiff enough to not deflect significantly.

I don’t know how stiff the cabinet stand is, but you can shim under it or under where the bed bolts to it.

I would not touch the headstock bolts until a great deal more measuring and checking has been done. Then *if* you

do need to at least you’ll know why.

Dave

Thread: edm machines
06/05/2021 18:37:58

I to have a mostly finished Ben Fleming EDM.

What are people using for the dielectric fluid?

Dave

Thread: Can one buy pliers with parallel jaws that lock like mol
06/05/2021 16:36:46

Parallel clamping in my workshop is done in a normal vice, or if larger than that will accommodate then with plenty of g clamps / sash clamps and flat bars.

You could remove the spring from the Maun pliers and add an elastic band or similar. Depends on how much force you need.
Kant twist clamps are another option

Dave

Thread: To gib or not to gib?
04/05/2021 19:40:57

Evening all,

I’m in the process of creating a Deckel like tool grinder, and have just fitted the work spindle housing to the xy table.

Work head on slide.jpeg

The dovetail has ended up smack on, with a lovely smooth shake free action.

I still have to fit locks, but currently it has no gib or space for one.

Given the block isn’t the hardest thing to reset to machine for a gib later I’m tempted to leave it off and fit one eventually when it has worn. The slide isn’t used in the general running of the machine, only to set tool positions and then locked.

Opinions?

More photos in an album, or on Twitter @solutionsByDave

Dave

Thread: Workshop and Drilling holes with an ER collet chuck
02/05/2021 09:34:55

For my mill I don’t even own a drill chuck. I have ER16 and 32 holders.

Its less faff than changing the Int40 to change an ER of either size, especially as the drawbar is tip

toe high.

Re Tidying up my workshop tends to go through phases of getting worse as I work, followed by a tidy at a good pause point. So it’s never really tidy, except for brief moments

Dave

Thread: Which type/brand of razor blades stay sharp longest? (cutting card/greyboard)
30/04/2021 07:32:41

IIRC they are stamped (blanked) out of thin stock in a long continuous chain, then run past a pair of normal wheels in a fairly continuous process. I’m sure YouTube will have a video.

no need for diamonds, AlOx will do fine

29/04/2021 17:47:22

Carbide is a bit of a catch all term. There are as many carbides as there are metals which will make them.

-Danger massive simplification ahead-

Tooling carbide is usually a powder metallurgy product, where small grains of tungsten carbide are held in a cobalt binder matrix. As a result there is a limit to how sharp an edge it will take - think of it like raisins in a fruit cake - you can’t slice as fine a slice as of a plain sponge. The raisins prevent it.(Not a very good illustration but possibly sufficient)

More expensive carbides are called Micrograin, and take a sharper edge because the grains are smaller...

The main advantage is that carbide is very wear resistant, so the not very sharp edge stays not very sharp longer than the sharper but less wear resistant sponge cake. If the sharp edge is ‘sufficiently sharp’ that’s a win overall.

Metal cutting tools don’t generally need to be that sharp (it’s a relative term), but they do need to be wear resistant.

29/04/2021 12:56:43

Re: Worn out Diamond stones: Try cleaning them. Something like WD40 and a toothbrush. I use diamond stones all the time in the workshop, and whilst I have worn them out it takes years of use even sharpening carbide and HSS tooling. But they do clog up.

Dave

Thread: Portable vice - buying advice sought
28/04/2021 19:09:46

The 702 ticks all of the must haves, 1 bonus and both not needed.

Didn’t see must not be alloy in the list.

28/04/2021 16:57:11

Stanley 702

Thread: Optimising the Life of Cut-Off Wheels
25/04/2021 10:59:19

A look for low speed abrasive cut off saws will also prove interesting.

For instance: **LINK**

I know it’s a 10” unit, but it’s *top* speed is 3000 rpm, and it runs down to 100...

Dave

25/04/2021 10:52:59

This:

fb77fa72-1fb3-4ed9-b120-5f072707ff67.jpeg

is a cut off wheel for a surface grinder. I’m not going to run it because it has lost its speed markings, but compare with a 41/2” angle grinder wheel:

c439bf97-0a3d-4b88-89a3-d262da945040.jpeg

3d682566-ab57-4ac3-bc17-d06235f65b75.jpeg

364e1cf9-f07c-45ee-81f5-5a7a05787934.jpeg


The surface grinder wheel is 3mm thick. I picked up a grinding rather than cutting disk for the angle grinder as it’s easier to photograph the edge, but essentially grinding and cutting disks for hand held use are pretty much the same (bar thickness).

Notice how the Surface grinder wheel looks the same in grit and such, but is missing the reinforcement mesh. That’s because a surface grinder operator is not likely to bump or twist the wheel in operation. No matter how careful the operator of a hand held grinder is their guiding ability is not the same. That reinforced wheel also has a higher speed capability- precisely because it is reinforced. That in turn means you can take a “bigger” cut with it because the number of teeth going past the cut per second are larger. A massive bonus for hand held work, as no one want to be holding the angle grinder for longer than required.

I have SG wheels which are basically worn (used) to the hub of the grinder so 4” or so. That they are used that far shows they still work ( most of them came second hand with my grinder).

Maybe later I’ll knock up an adapter hub and chuck a 1mm angle grinder disk in the bench grinder, but first I have a fuel pump to fit to my restoration project....

Dave

25/04/2021 08:47:38

There is little difference between a surface grinder wheel and a bench stone.

Think of abrasives as tiny cutting tools, taking a very small DOC on multiple teeth. (Somewhat true)

At that point you can see that to remove much material you have to make a lot of cuts - and to do that in a reasonable time your speed has to increase. Hence the general use of 'high' spindle speeds.

Dave

Thread: Small saw. Proxxon or something else
23/04/2021 19:41:49

@Dave S -
Interesting to know that 3000 RPM at 4inch diametre makes for good grinding. Whether that makes for good CUTTING on a 1mm abrasive disc I don't know.

Cutting with a grinding disk is grinding

I have some thin wheels for my surface grinder, which IIRC runs at a similar speed in terms of rpm. It’s surface speed is slightly more, as it has bigger wheels when new.
Angle grinder disks are reinforced to cope with gorillas mishandling them in the cut. Even so I think a 1mm angle grinder cut off wheel would run and cut fine at much lower rpm than a typical angle grinder runs. I’d go and try it if I really thought you would take any notice...

But given those numbers, can you explain why are all the circular table saw manufactures are all so adamant that their machines can't cut steel? If just don't make sense...

Product liability would be the first thing. If I designed a machine to use a course toothed saw to cut wood which is fairly soft I wouldn’t say it could cut metal which isn’t - that would lay you wide open to claims for failure.

Cutting metal generally involves higher forces, and most tools are built with cost as a major consideration. All then”cheap” table saws I’ve seen have pressed tables and large gaps around the blade. Not what you want for cutting thin bendy stuff. Wood at least will destruct as it tries to wedge into the blade / table gap.


> I do wonder if John S is trolling or just indecisive.
Back off. Absolutely not trolling.

I am a newbie but learning fast. However it seems that every time I am about to make a decision I get new information that renders what I was about to do a poor decision.

As I said somewhere in one of your threads the best decision, especially if you are up against a deadline, is to make one. So far I have seen something like 4 threads where you jump off into another line of investigation without having seemingly actually done anything with the information from the previous ones. You have impossible yet also imprecise specifications and don’t seem to listen when people say you can have that, but this compromise applies - usually it’s because you seem to want a Rolls Royce but only pay Robin Reliant prices or some other unicorn fantasy. You might be better to sub contract your machining, you won’t get new toys to play with, but your device could be finished. That would however mean properly specifying what you actually want and I’m not sure you know this.
Dave

23/04/2021 16:56:38


To slow for grinding appears to be a case of “internet knowledge”

My surface grinder is supposed to run 71/2” wheels iirc, so I didn’t look at that.

However:

77b25010-66ad-4f0f-a18e-15a2f8b3692a.jpeg
Bog standard bench grinder from B&Q. Takes 150mm wheels, runs at just under 3000 rpm.

Homebrew cutter grinder:

b437c0d6-cac1-4a6c-9e95-18975067cff4.jpeg

Has a 4” cup in it currently, also runs a 4” saucer.

Speed:

eae922b6-260e-4332-90c1-5f4f23803e9b.jpeg

Also just under 3000 rpm.

I have never needed to run a slitting disk on either, but I don’t doubt that with a thin wheel at that speed both would still work. Of course it would need to be the right wheel. Abrasive wheels are cutting tools, and much like different types of carbide or HSS there are different types of wheel. A wheel designed to run at 10000 rpm is built differently to one with a slower maximum speed.

I do wonder if John S is trolling or just indecisive.

Dave

23/04/2021 12:42:00

Seems to me if you had a small mill, somewhat like a sherline 5000, where the head can be set over at an angle then you could just use a slitting saw on an arbor.

As a bonus that machine could also do all sorts of milling things, and probably make precision V blocks with 90 degree included angles as well

Dave

Thread: Precision V-blocks (32mm & 7") - any UK buying advice ?
20/04/2021 19:12:42

Did a little measuring. The SPi blocks are as expected within 0.0001” in their pairs. The included angle is 89 degrees and 40 mins on the larger and 89 degrees and 50 mins on the smaller. So pretty close to 90, but just under.

The well used Brown and Sharpe pair are within 0.0003” of each other, but their angle is 91 degrees.

The vernier protractor measures 90 spot on with my “master square “ so whilst not traceable or calibrated I believe it for the roughness of these measurements.

Will 10 or 20 mins matter is something that the OP must decide, but clearly unless there is a spec and tolerance stated on the groove angle it might not be “exactly 90 degrees”

This is something to be aware of if you are planning to use a “precision” item for its none intended precision operation. Just because it was made with precision doesn’t mean it has the actual precision you need - unless the spec sheet says otherwise (and you can trust the spec sheet, but that is a different matter...)

Hope that is useful

Dave

20/04/2021 12:43:25

Funny how people use tools differently.
I use my V blocks all the time. So much so that I bought another 2 pairs.

Tjose ones are SPI from MSC and are, I would say, middle of the road on the price / performance scale - about £90 for 2 pairs of different sizes, claimed match to 0.0005”. They are numbered and I suspect match better than that as if you finish grind in a pair they really should be dead on.

Dave

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