Member postings for old mart

Got my letter today, 11.3% increase, whoopee!

I bought an 80mm Chinese three jaw scroll for my 7 X 12 lathe with the SANOU brand, not as good as Burnerd, but not rubbish either. Genuine Burnerd jaws would cost 5 times as much and as already mentioned, that does not help with general wear on the rest of the chuck.

When I was about ten years old, one of my friends shot himself in the index finger with one of those GAT pistols, it was not a pretty sight, more power than he had imagined.

When I was in electroplating, the firm came by the contents of a laboratory and included was a glass jar with picric acid in it, a yellow powder. I put some on a hotplate and switched it on max and nothing happened, very dissapointing.

I have a quantity of NOS soft jaws for the 80mm chucks with the 6tpi scroll, (4.24mm) pitch. The width is 9.41mm, slot is 4.85mm and the length and height are approximately 32mm. If you are interested, I may pop them on the classifieds at about £22 per set. They will not fit the later 80mm metric Burnerd chucks.

I have successfully hacksawed off the tangs of Morse taper drill chuck arbors and drilled them with hss bits. If you cannot find something ready made, you might be lucky and be able to get a 6mm hole through one. It all depends if the core is soft, though, I have drilled four MT2 ones easily.

The other way would be to hold the cutter in a lathe chuck and take small careful cuts. Not an ideal method as the chuck will not hold the cutter as securely as a proper collet.

Edited By old mart on 01/04/2023 14:22:24

A nice bit of kit, too big for the mills at the museum, a bridgeport size mill would be a good match. It must have been made for the German speaking market, by the Italian manufacturer.

Ah, happy days, my friend who had rich parents had a Brickplayer set and I was surprised to see one at a car boot sale about 16 years ago. I inherited Juneero from my cousin. My mother dragged a suitcase full of well worn meccano home from a jumble sale when I was 8, and that was still in the 50's. In the early 60's, a posher building set came on the market with aluminium angled sections with multiple holes in them, but I forget the name.As for calcium carbide and ammoniumtriiodide, I still have ten fingers and two eyes, must be lucky.

You really need to invest in another shape of insert and holders. For small ones, I would recommend DCGT 07 size inserts which are available in different nose radii and holders to suit them and the correct size holders for your lathe.

Unfortunately any mark on the bed will likely be obscured by the work or vise when the need arises for changing the height part way through a job. Possibly a straight ground bar could be fitted in the collet and in conjunction with the quill movement be brought into the same position after the head is moved. You would have to find just how true one would turn out to be by trial and error.

The lack of the cut at the back is good news, later batches of that mill would not have the bolt holes in them.

 Checking the tramm on the museums round column mill with a skim cut with an 80mm diameter shell mill gives witness marks in both directions when cutting one direction in the Xaxis, but only one set of lines when going the other way, good enough for our requirements.

Edited By old mart on 28/03/2023 17:43:41

Edited By old mart on 28/03/2023 17:44:38

I would be interested to know whether the cut in line with the column at the rear of the head exists or has been left out when the casting was machined. The centre line clamping which would be similar to the photo by Nicholas Farr would not be very effective if the rear of the head could flex. The two holes without bolts might have been a legacy from the last of the batch of castings still unused when the modification was made. If the cut is present, bolts could be fitted, but not tightened enough to prevent the head being raised and lowered and they would restrict any springing when the single clamp was tightened.

A lot of the drawbacks with the round column design can be circumvented bu careful planning before cutting metal. The quill has 5" movement and a lot of jobs can be completed without needing to move the head up and down. With a er collet chuck and a set of collets, you can also hold many sizes of drills as well as milling cutters and not have to allow for the much longer drill chuck.

If Diogenes is right, then you have come across the main drawback of round column mills. When the two nuts are slackened off to raise or lower the head, the spindle axis can swing right or left an unknown ammount which is a bother. This is not tramming but loss of position. We have one of these mills at the museum and I have fitted a laser on the right side of the head (facing the mill) and the beam reflects off a window about 12 feet away and back to a white patch next to the laser. With great care you can get about +- 0.001" as the beam is not perfect and the window glass nothing special.

Regarding drill chucks, they are not intended for used with milling cutters, firstly they don't hold well with the side forces, and secondly the chuck could fall off the arbor.

Edited By old mart on 26/03/2023 21:25:39

Edited By old mart on 26/03/2023 21:30:27

Edited By old mart on 26/03/2023 21:32:29

If the mill is one of the round column types, there is unlikely to be any need to tramm it. The only picture of an older typr of MD30B major I could find looks like this:

**LINK**

Nothing wrong with using a hacksaw to cut things chucked up in a lathe as long as you take care. The suggestion of a cover for the bed is excellent and easy to make.

Using a four jaw independent chuck to hold work that will be parted off helps with rigidity, a jaw every 90 degrees holds more securely than one with a jaw every 120 degrees, but some people are just too lazy or impatient to use one.The closer the parting off is to the jaws the better, if I needed to part off 2" from the jaws it wouldn't happen without tailstock support and then a hacksaw would be used for the final third of the diameter. Partial cutting with a parting tool helps with holding the final hacksawing square if you finish in a vise.

That chip shape made by carbide insert parting (which we use 100%) reminds me another advantage of rear toolposts using inverted cutters, the chips have gravity to assist their removal.

Sorry about mistaking it for a mill. If there is any of the spindle sticking out of the left end of the headstock, you could turn up a split clamping collar that could be used with a drawbar. It would be easy to remove when not in use. I have an er collet plate which is used on the lathe as well as the collets which are made especially to fit in the spindle. They have steeper angle tapers and are easy to remove. The er plate shares the same collets that the mills use and is easier to use than your Morse tapers.

All of my mishaps when parting off have occurred when parting by hand and never when under power, but that might have been just luck. When I see some peoples pictures of their parting setup looking as stiff as a wet noodle, I find it amazing that they ever manage to part off. When I bought my little 7 X 12, I was amused to find that the guy had been parting off with the HSS tool upside down.

The top of the spindle has been modified on some MT type mills to retain the drawbar so that it pushes the tool out. Unfortunately it may have to be removed and turned in a lathe, and the splines allowing the quill to move restrict the size at the critical top. You could look inside the spindle for a step just above the Morse taper, but there will not be much compared to R8 spindles, I have made two of these self extracting.

Check for endfloat in the leadscrew, and whether the saddle can be moved when the halfnuts are engaged. Also endfloat in the compound slide and in the spindle.

 Can you measure the max and min pitches?

Edited By old mart on 24/03/2023 20:01:28

Entirely possible, provided everything is locked and solid. The advantage is the steady feed rate and the fact that it is easier to provide a constant ammount of coolant. Tooling has to be in top condition as well. And as already mentioned, a rear toolpost will be more rigid and eliminates the compound slide flexibility.

Edited By old mart on 24/03/2023 19:47:06