Member postings for DiogenesII

bump.. fairly certain someone here will have the technique..

Edited By DiogenesII on 14/06/2020 09:23:38

..Heavens above - that's some screw.. ..are you making a cider press?

..Just been out for a definitive answer - I ground flats on the end of an old insert on my linisher - Zirconia will only just cut it (more like polishing, rather than shaping) and slow going, with heavy pressure (= belt wear) - I changed the belt to Silicon Carbide and removed more than twice as much material in c.25% of the time, with only light pressure. So No, not a practical proposition..

Any one know a source for Silicon Carbide Tape?

..I'd never realised that my neighbours were interested in Engineering Experiments, but when I finished at 7am, they all were at their windows, cheering me on and punching the air in excitement. ..Gratifying.

Hi Jouke, and JG - thanks for your interest.

I think in brief, that cutters will only have longevity in harder materials if the edge is kept within quite a narrow range of angles maybe only a couple of degrees either side of about 12 from vertical - less and the tool may start to rub, more and the edge becomes too thin and will lose strength.

I'm unable to contribute much to the thread during this week in any case, so if anyone wishes to experiment and post their own findings, it will be both interesting and helpful in keeping the thread progressing..

regards D

Thanks for that, it is much as I thought, except that on Sunday I hadn't thought of, er, the high-level advanced technique of using a strip of abrasive paper.. you clearly have more of a head start than either of us ever imagined..

And still I can't find a day to make chips. Work is the curse of the Model Engineering classes..

A Mr "Terry White 4" added a posting (his first) asking for help locating drawings for a 7 1/4 BR Brake Van on the "Tangential Tool" thread, so I have taken the liberty of starting a new thread here in the hope that his request might reach a wider audience..

"Terry W, Hi all,Im trying to locate drawings for a 71/4 gauge BR Brake Van,can any one out there help?"

Terry, hopefully the title will catch your eye, if you see this please leave a reply below then any members who can help will be able to advise or message you.. Welcome to the forum, and good luck with your search.

Mods, hope this is okay, feel free to do with this whatever seems right to you..

Bah - 9 humid hours of clipping Buxus Sempervirens, followed by the infuriating agony of "Microsoft Photos" mysteriously re-materialising on my PC and sending two years worth of pictures that MS didn't know I had back to Silicon Valley, presumably to be inspected for any identifiable brand logos and the faces of people who might be on my contact list.. Wish you joy with that..

So where were we? ..I used Niels' method of turning a cylinder of known radius and a feeler gauge to establish that the surface of the Hobbymat slide is 10.07mm (THAT much wear, eh?..) below centre-height - milling the toolholder to this height, so that the point of the toolbit can now be set by turning the holder upside-down on a flat surface..

I think I will accept Niels' challenge and make a dedicated holder to fit the Myford - I'm sure that I will not win a straight race, but maybe I can cheat, or think of an even more outlandish set-up.

I really need to get some new toolbits ordered - the small HSS drill-shanks are coming to an end, and because most have been used/chewed, I notice that although the overall surface finish is okay, using magnification shows that "Edison Phonograph Cylinder" effect.. Stoning, testing & stoning "old" 2mm rounds is one of those things that life may be too short to be doing much of.. I'll have to sell my television or something, and buy a 2 x 100mm stick of carbide. And a quality pin vice, maybe..

How and what do you sharpen your toolbits on, Niels?..

What a day..

Edited By DiogenesII on 08/06/2020 22:58:57

..parting a slot - now that is scary! ..I'll stick with a slitting saw..

Good morning,

I had some success measuring and milling yesterday, and some failure with surface finish.. ..unfortunately, the tedious responsibility of "work" intrudes today, I will post some photo's and a fuller text this evening.

That Thompson really is an interesting little engine - I can see why you'd want to model it. I'd guess that economy was the main driver of the design, but there's something very pleasing about it.

Nice, Look forward to seeing it come together.

Enviably logical! ..I wish I had that clarity of vision in the workshop.. A job for this afternoon..

Ha, I am being overtaken by posting events! Niels, to respond to your old post - it is gratifying to see that your CAD images are more or less identical to the holder as I have it - I made the nose angle 85 degree, but will make it narrower on the next one. I have filed it for easement and now need to experiment to see how tightly I can approach from the side.

Howard, I find that the 2mm bit (as I currently have it ground and held) is limited to a useable cutting depth up to about 0.25 mm - adequate for the Hobbymat, but I think there are probably better choices for bulk stock removal - it is possible Niels can achieve better, not least because he has spent far longer in refining his design, and has a more solid platform from which to work.

It strikes me that CAD may hold the definitive answers on cutting depth, which will surely be tied to the logical mathematics of an acutely-sectioned cylinder?

As to setting, in practice, I find that because the cutting edge is plane and somewhat reflective that orientation is easily established by eye and intuition, although being plane, it ought to of course respond to the attentions of a small but easily constructed setting jig.. Another thing to get round to!

Slitting saws - I think I must have started to use them whilst I was unaware of the dangers, and so they do not cause me any concern - use a speed at the lower end of the required m/m, feed by hand gently until the teeth are fully engaged in the slot and thern you can up the feed rate just a little to keep it cutting cleanly - maybe you know that "hissing" kind of noise when steel is cutting nicely - like that, and like all sawing, best results by not pushing too hard, just each tooth cutting off a nice chip.

For a small job, I'd rather go slow and not use oil, than use oil and have the chips turn to a sticky mush in the slot, better to keep them free to exit. Never use CT90!

The centre height is about 10.5 above the slide, but accurately measuring is first job of the morning!

Sincere thanks for your advice so far

Good morning

For my own part, I have experimented with round tool-bits in the past, and have found 3mm or 1/8" is probably about the useful limit on the small machines I have (I have a tired ML7 as well) if chatter is to be avoided.

Niels, to cut the slot takes a keen eye, and a steady hand - and a .050" slitting saw - I considered hand sawing, but like you, I find it leaves a finish that is not good for public viewing. No-one will ever see pictures of my mandrel handle!

Many thanks, both;

Howard - your information is a useful reality check, and confirms my thoughts on the necessary angles - the toolbit is ground at c. 24 degrees and inclined at 12, so I feel some reassurance there. For the current "testing of the principle", I've been using a "clog-heel" type clamp so that I can quickly swing the tool between the necessary orientations required for "turning" and "facing" - I do recall the "inclined-base" version, and will refresh my memory again, thank you for the prompt. I agree regarding the utility of a centre-height gauge, which I already have, and indeed, dovetails neatly into the observations of...

Niels - very canny, the holder will be going under the mill tomorrow and will emerge 2.2mm or so thinner along it's back.. I will not have to fish in oily swarf for the tiny hex key ever again..

Are you able to both side & face with it in one position? .."sharpening" the angle of the nose, without thinning down the clamp "jaws" is becoming the most head-scratchingest part of the job.

I'd like to see more of your build if possible..

Hi, thanks old mart, I hadn't considered making it a double ended, but that's a logical plan for a test bed.. It'll also be convenient 'cos as you can see in the second photo, it was the last end of the bar..

In a recent update to an ongoing thread (Lathe Improvements?), Niels Abildgaard included a photo of a machining setup which featured a short, stubby tangential toolholder which barely overhung the edge of the topslide - The design commended itself to me as a Hobbymat owner, as I've always regarded the standard toolholding provision to be, well, less than perfect, perhaps.. The Hobbymat does not respond well to excessive or uneven loads applied to the surface of the topslide, and the tools must be shimmed to centre height - the opportunity to try and alleviate some of these admittedly minor annoyances and to be able to employ a simple and easily set tool for the most commonly undertaken, facing and turning tasks seemed to be worth an experiment.

I quite shamelessly set out to produce a smaller but more-or-less identical version of this toolholder with the aim of trialling it, guessing at the angles (12 degrees for toolbit and back rake, 85 included at the nose) from extra photo's that Niels kindly posted.

The initial results are promising - the holder was relatively simple to make, cuts well (when arranged not to rub - see below) and sits firmly on the topslide without having to apply brutal levels of torque to the clamp. It's currently fitted with a 2mm round HSS toolbit.

The tool as it currently exists is very much a "first-off" and I throw it out here, naked in it's imperfections, for scrutiny or comment by anyone interested.

I'd welcome opinion on whether the 12 degree toolbit angle is in the right ballpark or whether it could usefully be increased to provide more clearance without increasing the risk of weakening the edge - and will I need to change it if I wished to use carbide?

There is a "To Do" list - I clearly need to reduce the height of the upper face/front chamfer to avoid the nose rubbing, reduce the included angle of the nose to provide more side clearance, and experiment with tool-grinding angles to find the optimum balance between cutting angle and edge-strength. And I may move the clamp screw rearward just a little..

Any comments and suggestions will be gratefully received

Edited By DiogenesII on 06/06/2020 19:55:27

'pologies if this is teaching granny etc., but I find that even the slightest failing to ensure that the chuck is run completely onto it's seat before starting invariably leads to it sticking..

Has anyone ever used (or considered) a LH-threaded nut on the end of a mandrel inserted through the chuck to hold a spindle whilst loosening a chuck?

..or clamp to a small angle plate (imagine something like IanT's table mounted vertically on the mill..). ..or even mill up a piece from the scrapbox to make a holding fixture, if it's something you do often.. ..something like a block with a rebate in it, and a finger clamp..

Edited By DiogenesII on 04/06/2020 06:43:36

As mentioned above, one can simply machine opposing shallow tapers - 2 degrees will do it - and blend using a file.

This tracks fine with 6" pulleys at 2850rpm, and the tracking adjustment is capable of putting the edge of the belt exactly on line with the edge of the platen (and keeping it there) if needed. Both of the wheels have a shallow 2 degree crown.

..sounds like Glandular Fever to me..