Member postings for old mart

This is how Tom Senior mills lock some of their gibs. It would work with the multi screw type, but not a tapered gib for obvious reasons. Drilling the gib could be a problem if it is hard and you don't have any solid carbide drills.

My memory could be at fault, but I thought the knee lock screw pressed against a captive brass piston which was in contact with the main body of the mill. The gib has a hole through it for the brass piston. If the gib is adjusted and then locked by the bolts, the lock screw would not work just by pressing on the gib.

Nigel is correct about the swivel base for the vise, only fit it when you intend to use it. We have two Bison 100mm vises at the museum, one came with the drill mill and the other I bought at a bargain price new with a swivel base. Mike was using the Tom Senior with the newer vise, and I was using the drill mill with the older one with the swivel base fitted to it for the first time. I lined up the scale as close as I could, (the base has keys) and the rear jaw had a run of 0.004" in the full 100mm width. That shows just how good Bison are, the heights are only 0.0005" different too.

I shall have to look at M- Machines website. Found it and bookmarked it for future referance.

Edited By old mart on 31/10/2020 21:04:01

As I recall, the bolts have some clearance in the casting and are threaded into the gib. They need to be slightly loose, say a couple of foot pounds only so that the adjuster locking screws can push the gib into the dovetail, then the bolts are tightened. It is one of those frustrating adjustments which would get easier with practice, but with only one knee to adjust, you are not likely to actually get much practice.

That 0.00039 figure with the DRO sounds like some conversion between imperial and metric, 1mm is close to 39 thousandths of an inch.

Put Tom Senior in the keyword and manual machines in the topics at the top of the page, and then save in your browser favourites. There is a wealth of info to read through.

I would get solid carbide 5mm drills for hard material and forget reaming.

If he painted the vise to match, he would have had a job finding it.

I use a set of three Moore & Wright teliscopic gauges down to 3/8" and. then some of their ball gauges to 3/16". They are good enough for 0.0005" with practice.

I was just as baffled by the strange gib adjustment on the TS knee. Our one is easy to move in the top 2/3 of the range and then gets tighter in the bottom 1/3. This is the standard wear pattern presumably, and I might try and do something about it when the new knee nut is made. Because the large ammount of backlash in the nut caused by wear would not normally be noticable because of gravity, I chose to ignor it when the mill was put into working order. The tightness of the gib at the lower part of the travel causes sticking and then the whole assembly drops suddenly which I don't like. I don't know yet how much uneven wear there is in the leadscrew until it is removed. I would be over the moon if I could get the knee to 0.00039" on the museum's machine.

I am tempted to cut up the spare Smart & Brown model A leadscrew which I have, to make a replacement for the TS knee, it is 1" X 6 tpi ACME, which would require a new scale for the mill. I know it will never be needed for the lathe, but it seems just too vandalistic to contemplate until the TS knee screw is examined. I can even out the wear by singlepointing on the lathe and then make the new gunmetal nut adjustable for backlash.

Edited By old mart on 31/10/2020 19:06:19

I have machined several, including one from solid instead of cast to rough shape. I used all the magnets available and should have used a vacuum cleaner as well. The nicest type of cast iron to machine is tha ductile SG type, (spheriodal graphitic), none of the dreaded black dust.

Amazon seem to have found a way around every type of tax.

I found a seller on e--y UK in a couple of minutes, all lengths available.

I don't push an eighty shell mill very hard, its the diameter that interests me rather than large chips flying about. Still even with 1/2mm of cut in cast iron or steel, the feed rate has to be fairly low. I listen to the sound of the motor, the six pole one has very good torque, as it runs below 1000 rpm at 50 Hz. The lower bearing for the spindle is one size up from the standard taper roller for an R8 spindle, the upper is the original size that TS fitted. The pulleys at the front run on needle roller bearings rather than the more common for TS bronze bearings. One of the reasons for going to R8 was the large quantity of R8 tooling we have at the museum. The conversion was very straightforward, but we had the great advantage of having a lathe and mill available to use in the workshop.

I have just got hold of a piece of gunmetal, 45mm diameter with a 17mm bore and 135mm long. It will be cut in half and make a new nut for the knee which is 1" X 5tpi LH ACME. Having a hole is great as I only have to bore it to 0.8" for the thread, which will be singlepointed on the lathe.

Edited By old mart on 29/10/2020 20:07:15

Edited By old mart on 29/10/2020 20:15:28

It is useful to have the lathe option, I also have a lathe mount, but it was bought some years after choosing er 25. I found that the cheap sets of collets were a bit of a lottery regarding accuracy. I have some Cutwell and Vertex collets in the most used metric sizes for milling cutters, (6-8-10-12 and 16mm).

Not wanting to start yet another TS thread, I have an improved leverage handle for the knee. This helps when there is extra weight on the bed, especially when the knee is near the bottom of its travel as there is less wear and the gibs are tighter. The handle I bought has seven indexing positions and I just made the mating adaptor on the rotary table at the 51 degrees and 26 minutes, which is not exact, but fitted perfectly first time. I was lucky guessing the crank on the handle, as there seem to be lots of variations for sale from numerous old mills. It just clears the tray at the lowest position without anymore than the minimum shaft extension. Most of the time, the original wheel will be fitted, but I like having the choice.

Edited By old mart on 29/10/2020 18:15:27

The difference between the drawing size of 31mm and your measured 34mm is probably of no concern. Try measuring the diameter where the witness mark is, the extra rust would show where the tool does not enter the spindle. The 30 INT size is a step up from R8 and tooling in that size is not too hard to find. Modifying the spindle to R8 would be difficult, and the taper angle is not the same as 30 INT.

One thing I found, that with the LV, you do not have to remove the motor to change belts. Just slacken off the pivot and locking fixings about 1/4" enables the motor to be lifted up by a couple of screwdrivers as wedges and the belt can be slid under the end of the pulley. The drawbar should be removed and the quill extended to get the belt past the front pulley.

Ah, a picture which explains everything. The pairs of clamps touching are the prime suspects, strange that both sets should fail to clamp at the same time. This type of clamp is featured on the Light Vertical quill, the drill mill quill, the drill press and the lathe tailstock, all four of the machines at the museum lock perfectly.

The Tom Senior light vertical at the museum runs an R8 spindle upgrade and a 1hp motor rather than the original 1/2hp one. I fitted the 10mm link type drive belt to the machine, but it has proved not entirely satisfactory. Running up to 80mm shell mills has put more strain on the belt than expected. The trouble is that the belt has gradually sunk deeper into the vees of the pulleys and the metal washers on the link pins have started to rub against the soft aluminium, leaving a slight groove. I don't want this to happen, so the standard type of vee belt has been fitted. The size that fits this four speed machine is Z 18.5 10X 495Lp- 470 Li.