Member postings for old mart

Just the thought of it makes me giddy. Many years ago, I had a little control line plane powered by 0.76cc Quickstart diesel engine. The fuel tank was on the back of the engine, but I thought I was being clever to ditch that and fit a metal tank of about five times the capacity. Big mistake, by the time it had run out of fuel, I was feeling quite ill.

INT30 is superior to R8, although the industry standard is INT40. My old firm used INT40 on all the CNC's and INT50 on the two biggest manual mills, the toolmakers had a couple of Bridgeports with R8.

 Vic, that mill you had with MT2 and INT30 sounds like a T S M1 to me, you will appreciate why I modified a light vertical spindle from MT2, to R8. Changing it to INT30 would have been too ambitious.

Edited By old mart on 13/06/2020 20:56:19

Photos of both sides of the chuck would help. The  common type are just pushed in with an interference fit. You will probably have to make, or modify a thin punch to knock the offending one out. Before you do that, scratch a line across the plug and the chuck body to help line it up when you refit it. I have removed the plugs from three chucks successfully. Also number them if taking more than one out.

Edited By old mart on 13/06/2020 20:43:07

The op's question was answered immediately, but, as often happens on almost all forums, the subject matter has wandered in various directions. I am as guilty as anyone else.

I normally go to the latest post, but also have "Tom Senior" in the favourites in my browser, which links directly to all the forum posts for that make of mill.

SOD, your illustration with the red highlights conveniently leaves out the top end of the R8. Why is that?

The point where the lack of diameter in the MT3 makes it more  flexible than R8 is where the tool emerges from the spindle.

Edited By old mart on 13/06/2020 13:53:53

That spindle will be ok, the score is less than 10% of the area. I replaced the thrust race on the Model A with a metric one, I think the bore was the same as the old one, you would have to do a bit of research on the sizes for the Sable first as the design differs.

I have just bought a Sandvik boring bar, it is 25mm diameter, but the cutting height is more like 12mm. I would guess that the minimum size of hole for it is about 40mm. It will have to have a custom mount made, and I will have to mill 2.5mm flats on three sides of the shank. Even this large size bar has a recommended max depth of only 100mm, 4X the diameter.

I don't understand how the forces differ from front to rear parting. What matters is the stiffness of the setup, the removal of the compound helps, as does not having a QCTP on the front with the associated overhang and extra joint. Keeping the cross slide gibs properly adjusted and as near to zero leadscrew backlash as is possible helps. As the rear cutoff forces are upwards, the saddle must not be allowed to lift and it should ideally be locked down securely if possible.

Get a vacuum cleaner set up to deal with the mess.

Hi, Damien, you must be optimistic, trying to get a Myford where you live. There can't be many on offer there. Due to the popularity and abundance of spares in the UK, Myfords always sell for premium prices here. There is a top of the range Super 7 model in new condition going for £7500 at the moment, nice, but it won't do anything that an Atlas in similar condition would be capable of.

Size and stiffness wise, R8 is equivalent to MT4, not 3. The 30 ISO is a step up from R8 for small to middling mills and more desirable, but not so many machines use it. ISO 30 tooling is fairly easy to get hold of, but nothing is as common and plentiful as R8.

It is possible to buy thick walled steel tube, which might be cheaper than the cost of tools to drill a deep hole.

If you do your own drilling, then get quality new drills and drill both ends with a jobber, then switch to long series. If that is not enough, then think of attaching the jobber to an extension for the last bit. You might benefit from drilling 1/4" which will give a bit of leeway in the event of a mismatch. The whole job will take some time as you will have to clear the swarf every 6mm or so.

Edited By old mart on 12/06/2020 13:28:01

I would only recommend R8 over MT3 if the machine had not been purchased at that stage. The recommendations for er32 are sound, just make sure that there is provision for both spanners on the tool. I have found that the standard length spanners are not long enough, so I found some tube to extend both to at least 300mm, 1 foot long. Then you can tighten and slacken off without disturbing the tool in the spindle. After the initial slackening, the nut goes tight as the collet is broken free from its taper. You must have something soft like a wad of rags to catch the cutter as it falls. I have found that buying a full set of collets ends up with some never being used. I think it is best to buy collets to match the sizes of the cutters you have, 6, 8, 10, 12 and 16mm are common shank sizes for milling cutters.

An extract from Smart & browns instructions for their model A toolroom lathe:

Welcome Martin, You have made a pretty good start with machinery, and there will be plenty of steam engine enthusiasts to guide you in your projects. This unfortunate CO19 lockdown has encouraged a lot of new members to make the effort to join the forum, its an ill wind...….

I wonder if George Thomas ever tried to produce a standard 60 degree taper on the end of a centre with the tool height off centre. Anyone with a brain cell would be able to understand what the outcome would be.

I have the lathe taper turning attachment set for MT2. It was set by length bars and trigonometry, but even that didn't get it exact. It ended up finally by trial and error using a MT socket as a gauge to feel the exact angle. Unfortunately, R8 sockets to test don't seem to exist, unless you have a mill spindle laying about. It is important to have your tool height exactly dead on or the taper will not be a cone.

I don't attempt to make an R8 arbor from scratch while soft ended blank ones are easy to get hold of.

https://www.ebay.co.uk/itm/RDGTOOLS-R8-SOFT-END-BLANK-END-ARBOUR-7-16-UNF-DRAWBAR-BRIDGEPORT/370487538089?hash=item5642c731a9:g:2~QAAOSwolVc-hCl

Edited By old mart on 10/06/2020 21:47:44

Edited By old mart on 10/06/2020 21:50:44

ega, I did incorporate that offset into the rear toolpost that I made for the museums Smart & Brown model A and also added a rear lock for the saddle, so with two locks the saddle is pretty solid.

It depends how long the bar is. I have two 5" and one 2" at the museum, and I recently saw a 10" one on ebay. There are probably plenty of metric ones about as well.

Just put this calculator in your browser favourites:

http://www.carbidedepot.com/formulas-trigright.asp

Edited By old mart on 10/06/2020 19:33:35