Member postings for old mart

I know what a B50 barrel is made of. I didn't like the tool because of that first generation style of insert in it. Times have moved on and there are much improved indexable tools on the market. How much metal do you intend to leave in the bore for the honing?

If I was going to attempt that boring of the cylinder, I would not use that tool, unless there are inserts suitable for aluminium available for it. The aluminium grade inserts are sharp, and can be used with very small depth of cut, which would significantly reduce the forces on the bar. I would get one of these which use WNMG 08 inserts. I have some cheap Chinese inserts for aluminium which are surprisingly good when used on steel and CI with small cuts, right down to 0.0005".

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Were you aware that the recommended diameter to length ratio of a steel boring bar is 4:1, solid carbide is 6:1, the most expensive bars can go to 10:1, and they cost somewhere in four figures. That cylinder really needs a 3" diameter bar, and a much bigger lathe.

I do hope the op was taking the mickey when he said he was filing the tee slots. Or at least only filing the front side of them, otherwise he has wrecked a brand new table. Those slots are dead straight and exactly parallel to the X axis for a reason.

 Making tee slot nuts which fit the slots better than the bought ones is a good idea, they spread the loading better, Mike is making some out of key steel for the Tom Senior, they are also 20% longer than the bought ones.

I worked as a fitter in aircraft engineering but certainly not as a butcher as described.

Edited By old mart on 02/11/2019 20:52:47

Edited By old mart on 02/11/2019 20:56:44

The quill will need 1 1/2" overlap when in the extended position, and this is added to whatever travel it has. This is why I thought one of those sidelock holders might be suitable. Of course, the seller does not include the length of the bore of any of them, so its pot luck.

Its a difficult project, what with the core diameter of the pull stud being only 9.85mm and some method to allow the chuck shaft to move axially and turn with the toolholder via a keyway or similar. The stroke will be severely limited, if the whole assembly is not fairly long.

These sidelock spindles may have the answer to the finish of the bore and the screws could drive a slotted spindle.

**LINK**

Just a thought, but these boring heads are screwed onto the arbor, and if you have a lathe, you would have more options to design the keyed sliding part, and also have a boring head at the same time.https://www.ebay.co.uk/itm/SOBA-50-mm-Boring-Head-Complete-with-Tools-INT-30-Shank-Metric-17113030-ISO30/372164615910?epid=3011275466&hash=item56a6bd5ee6:g:kRIAAOSwDFBaL9SP

An er32 collet holder also has a thread which has potential.

Edited By old mart on 01/11/2019 19:47:58

Edited By old mart on 01/11/2019 19:50:51

DRO,s are nice on a lathe, but not vital, I would spend the money on tooling. On a mill, not having a DRO is a great disadvantage.

I looked on ebay, and there were er32 holders up to 140mm long in diameters up to 32mm, also MT 2, 3 and 4. The straight shank would fit in a four jaw independent for fine tuning the runout, and be adjustable axially.

About 3 years ago the museum had a visit from two young ladies from health and safety, who looked at the machinery and really didn't know much about any of it. They were probably more at home in shops and restaurants. I thought that something ought to be done about the lathe, which had next to nothing in the form of safety devices. I bought a cheap stop button which got glued over the ancient one, at least it is much bigger. I was talking about making a chuck guard, when Chris said that he had seen one up on the mezzanine amongst the bits and pieces of helicopter. It was exactly the right size and is now on the lathe with an industrial microswitch which I had saved from being dumped as surplus from my old firm. Having the microswitch saves me from bending down to stop the lathe, which is welcome. They never came back, all the radioactive things that this sort of museum has must have put them off.

I use full profile threading inserts, they are the proper shape for the job.

I remember riding a motorcycle along the Hogs back between Farnham and Guildford (A31) and seeing a Hercules very slightly below me to the north.

Dead right Michael, the problem is that the threads in the tooling are not always exactly in line with the axis of the spindle. The drawbar of the drill mill is more forgiving due to slight wear. There are a lot of tools to test out on the TS, just running the tap down has cured most that I have tried. Having a self extracting drawbar will make the tight ones more difficult as they cannot be slammed home in the taper before engaging the drawbar. However niggling these problems are, I will not put pins in the spindle, or change to a loose drawbar. now I have experienced the advantages of the present setup.

 I wonder if the ISO30 spindle could have similar problems with the drawbar thread being tight?

Edited By old mart on 27/10/2019 19:15:43

Edited By old mart on 27/10/2019 19:16:28

Welcome, Jurrian, your lathe looks good, maybe a toolmakers lathe, it is very heavily built for its size.

I had a B & D D720 drill back in the late sixties and when I took the cover off the side of the handgrip to look at the switch, I was horrified to see that the insulation had gone hard and was cracking off. This was in the early eighties, the drill got binned immediately, especially as it was metal and predated double insulation. I suggest you check all of these old drills for safety, especially the earth wire connection.

I would just cut a bit of 1/2" thick aluminium plate to the size, drill a hole the same size as the sides of the square spindle and hand file the square until it fitted. The handle would be even easier to make.

We have a full set of metric, and several imperial R8 collets and I have had an unforeseen problem with one of the first ones I tried using on the Tom Senior. The TS is converted to R8 and I elected to leave out the pin in the spindle which is there only to stop the tooling from turning when the drawbar is being tightened. The drawbar is newly made and can be slightly tight in some of the tooling. This happened with the 5mm collet which I wanted to use, and persisted even when I ran a 7/16 UNF tap down the threads. The downside of the collets is that there is nothing to get a grip on if they turn with the drawbar. I may have to drill three axial holes in the collet nose to use a pin spanner. The spanner would have to work with the 20mm collet downwards, so I will have to be careful with the positioning and size of the holes. A job for the rotary table with a chuck on it, and maybe a small carbide drill. I will do them all to prevent an occurrence of the problem.

I have two other types of stop, and I had never thought of this design, I must add it to my list of things to do.                 It will fit on the ARC vise, but the Bisons have only got about 1/2mm jaw projection

Edited By old mart on 26/10/2019 22:25:47

The Tom Senior light vertical mill we are doing up has a tilt feature, and the head can be moved out to give about 5" more throat depth. It is primitive compared to a Bridgeport, but could be useful one day. There is a straight ground surface on the left side of the head, and I have tried tramming it with a dti. A test with 63 or 80mm shell mill will find out whether or not I have to make a conventional spindle mounted tramm.

I find that with a lot of things, there is a much better way to do them if only I had thought of that at the time. I like a challenge, I go for the "if I don't do this, it will never be made", and its a good way to learn.