|Charles Jarman||27/09/2019 11:33:57|
|11 forum posts|
Yes Andrew, I quite understand that, hence looking on you tube at those exact materials.
Yes they’re cheap, so no love lost if they break or do not come up to expectations, but that’ll be part of my learning process, in understanding and being to evaluate the good and the bad.
regarding materials, my job involves dealing with all sorts of waste including metals, so not only can I source free materials, but get an education in where they are used.
|Clive Foster||27/09/2019 12:18:47|
|2205 forum posts|
+1 for what Andrew says about known material and sharp tools.
Lot to be said for splashing out on some delrin, which cuts easily and is very well behaved, and proper free cutting mild steel to start with. I've had a few bits of material that were far harder to cut than they should have been despite being ordered under a proper type number from reputable suppliers.
For sharp tooling I'd not worry too much about "book" profiles and angles. These are fundamentally for larger machines taking heavier cuts in industrial practice. You will, initially at least, be working with cuts of less than 50 thou / 1 mm so the actual dimensional difference between book profiles and "really easy to keep sharp" will be minimal.
Hollow ground profiles are much easier to keep sharp than flat ones but they are fundamentally weaker and don't stand up to industrial loads. Which matters not at all to a Unimat user.
I'd obtain a half decent 6" or, better, 8" bench grinder and set the toolrest level with or just above wheel centre line. Generally anything above the stupidly cheap machines do a very acceptable job of actually grinding. Weak points are toolrests, invariably flimsy and hard to set just so, and wheel dressing. Can be coped with initially and fixed at leisure.
Make your basic tool from a piece of square HSS of appropriate size. Grind about 3/8 - 1/2" of the long, leading edge side, on the periphery of the wheel taking just enough off to give a hollow grind and sharp edge on top. Keep the grind parallel to the body. Now do the same on the front end of the tool with the edge leaning back about 10 or 15° to give clearance. Finish off by swinging it round to give a small radius on the sharp tip. A mm or so should do. Make another the opposite hand so one cuts moving along the bed and the other cuts going across. I say job done. Other folk say put a similar hollow on the top which does give a better shape but whether it makes any real difference at sub mm cuts I doubt.
If you have a slipstone or diamond hone rubbing it across the tool will make it even sharper. The hollow grind supports the slip or hone at the to and bottom so its easy to keep it properly aligned. With a flat grind its very easy to rock the slip or hone leaving a nice polish but taking off the very sharp edge you are trying to achieve. Only takes a few bad strokes to spoil things. Needs a microscope to see the damage so you will never notice the error. Just be monumentally frustrated wondering why your newly sharpened tool isn't cutting like it ought to.
After the first sharpen and hone work on the front edge and point radius only. Unlikely to need proper re-sharpening until you have honed a flat 1/2 a mm to a mm below the cutting edge.
There are a lot of ways of producing a good cutting tool. Most folk have their preferences and have sorted methods which work for them with the equipment they have and suit the jobs they do. Plenty to investigate once you get the hang of things. For beginners easy to make, easy to keep sharp and works pretty well will do.
Edited By Clive Foster on 27/09/2019 12:19:57
|Charles Jarman||27/09/2019 12:34:05|
|11 forum posts|
Thanks Clive very informative. As I’ve mentioned, I do look on YouTube for working practices, the first being on tool sharpening and forming, looking at the differences between carbide and hss. Knowing what tools to have in using my SL will come, eventually.
A lot of what I might make will be with Aluminium and certain plastics that I can use in my RC aircraft hobby, no real challenges for me or the SL.
18118 forum posts
Your cheap holders will likely do for now but worth getting a few decent inserts and for aluminium, plastics and other non ferrous I would suggest the ones made for aluminium which will have a code **GT depending on the shape of insert you have chosen.
|Charles Jarman||27/09/2019 12:40:14|
|11 forum posts|
|old mart||27/09/2019 16:40:45|
|1771 forum posts|
Its a shame, I just looked for M12 X 1 nuts on that unmentionable site and had a choice of half nuts, full nuts and stainless steel ones.
|Howard Lewis||27/09/2019 18:24:55|
|3272 forum posts|
Already, you see the help and advice available.
Have you now got your 12 x 1 nut?
Whereabouts are you located?
PM me if you are near the Cambridgeshire / Leicestershire / Lincolnshire borders.
At the risk of Chicken and Egg, if the lathe cannot be used to make a Tee nut, you could hacksaw and file up a Tee nut. The stud does not have to have a 12 x1 thread, there should be enough meat in the Tee nut to put in a standard Metric Coarse 12 x 1.75.,
If the nut is a bit too thin for M12, and the lathe is runnable you could turn up a shouldered stud , (Presumably, it is for a Toolpost? ) so the lower end could be M8 or even M6. (You would be surprised just how much load you can produce with a M6 thread! )
With a bit of ingenuity, you can get the lathe useable, and then start making "neat" fittings, and accessories for it, before you start on your model making activities.
18118 forum posts
Howard, tee nuts are threaded M6 into an 8mm wide slot. Spindle pulley is retained by M12x1 nut
|Howard Lewis||27/09/2019 18:53:36|
|3272 forum posts|
So if a 12 x1 nut is available, for the spindle, to get started, a bit of M6 studding and an M6 nut, would start the ball rolling, to make a proper stud.and nut combination.
For a "bodge" Tee nut, turn a bit of steel to 12 or 10 mm diameter, to the right thickness for the bottom of the slot.
File a couple of flats to give 8 mm, drill 5 mm, tap M6, et Voila! you are up and running and ready to make whatever "proper" bits you need. Next job, repeat, but with a stem, say 7.5mm dia?
Starting to sound like "There's a hole in my bucket, dear Liza, a hole" aren't I!
Possibly, a tee nut would be available commercially, if filing does not appeal.
Edited By Howard Lewis on 27/09/2019 18:55:18
|128 forum posts|
One of my first lathe bodges was filing two parallel flats on the head of a cup square head coach bolt to make a passable tee bolt. It needed a little refining of the square shoulder to fit the tee slot without binding. Often it is irrelevant whether the nut is on top or bottom, although clearly not always the case.
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