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Member postings for old mart

Here is a list of all the postings old mart has made in our forums. Click on a thread name to jump to the thread.

Thread: Which is better Thompson or er collets
14/08/2021 20:42:03

There was a time when every company which ran Bridgeports used the screwed shank tooling, I have a box of about 1000 blunt cutters left over when I weeded out the sharper ones for the museum. The posilock type of collets are still available new, they are the type that the Osborn Titanic II uses.

14/08/2021 19:11:35

Chris, the top picture shows the folding links which keep the upper and lower parts of an undercarriage lined up with each other. I have seen this applied sucessfully to a round column drill mill.

Terry, you will get better results if you shim the mill where it bolts to the stand to get the bed horizontal. If you don't have a reasonable level, a ball bearing sitting on the bed should not move.




Edited By old mart on 14/08/2021 19:15:02

Edited By old mart on 14/08/2021 19:15:30

13/08/2021 21:45:48

One way of keeping the vertical movement is a version of the aircraft suspension, using a pair of folding links with close fitting bearings. They are normally fitted at the back of the column.

Thread: Consequences of Machining Cast Iron
13/08/2021 21:33:03

I remember how deglazing brake drums in the sink used to leave little brown spots stuck all over the stainless steel.

13/08/2021 20:03:12

Your tilt measuring device is not sensitive enough. I was going to suggest that you match the tilt of the line to that of the table, but a tenth of a degree would be on the coarse side.

Assuming 4mm at 6 metres and reducing that to whatever your column to spindle distance is would give an approximate movement of the spindle sideways. Say the column to spindle centre distance was 333mm, then the angle moved would be 0.0382 degrees, and the spindle would move 0.222mm. I use the reflection back to the end of the laser which would double the effective distance.

It would be nice to find a laser with a smaller diameter beam, mine is similar to yours. Estimating the centre of the beam should give better results. Make sure the lens of the laser is clean.

Your dial gauge should be 90 degrees further around the quill, either direction, so that movement in line with the X axis is measured.

Edited By old mart on 13/08/2021 20:09:23

Thread: Which is better Thompson or er collets
13/08/2021 19:31:18

I use both, but using the threaded milling cutters has one disadvantage, most are HSS. I do have a few threaded shank cutters with inlaid carbide cutting edges. I believe that a thread on the shank of a solid carbide cutter would not be strong enough to be viable. The er system can hold both HSS and solid carbide.

Clarkson, Acramil and Osborn are three makers which can hold the threaded cutters by default, er can also hold them as long as the threaded end can pass through the collet body.

Thread: Hole diameters for single point threading
13/08/2021 15:31:24

You will find that any given pitch of thread is the same depth, ie, a 6mm X 1mm pitch thread depth would be identical to a 20 X 1mm pitch thread. So if you need to make a unique diameter thread with a standard pitch, you can use the figures for that pitch of thread. If possible, you can get a perfect fit by using the mating part as a gauge and creep up on the last bit. If the fit is critical, but the mating part cannot be used as a gauge, you could make a threaded gauge of the same size to use instead.


Thread: Belt lacing clips
13/08/2021 15:06:23

The Smart & Brown model A uses a 25mm x 3mm thick belt with a join in it sucessfully, I believe the belt and joining parts came from Lathes UK. I'm not sure if a 2mm thick belt can be joined mechanically, though.

Thread: er25 collet
13/08/2021 15:00:14

I would feel safer using the full length of the collet. 16mm collets will always be full length inside.

Thread: Bearing out of position - how to correct?
13/08/2021 14:56:35

Howard's suggestion of sharing the rework at both ends would be my choice if there was enough material.

Thread: Making Tapered Castellations in Aluminium
11/08/2021 20:27:04

I used the rorary table to produce a similar type of drive, but with 7 segments, 51 degrees 26 minutes, approximately for a long handle for the knee of the Tom senior mill when there was a heavy weight on the bed.


Thread: A robot of many colours
11/08/2021 19:38:11

It is amazing exactly what some people get up to to justify their existance.

Thread: Vise/Vice advise
11/08/2021 19:28:40

_igp2821.jpgThis is what the museum's drill mill looks like with an ARC 125mm vise and also with a 100mm Bison vise. I bought the ARC vise for its extra opening for a larger job. The drill mill is one of the larger sizes, the bed is 8" by 28 1/2" and has a 500mm X travel.





Edited By old mart on 11/08/2021 19:30:44

11/08/2021 19:20:41

It's very satisfying to hear of a sucessful outcome, your machine is better than new now and everyone has learned something to boot.

Thread: Vise/Vice advise
10/08/2021 19:47:12

For that size milling machine, a 4", 100mm would be the sweet size, with 5", 125mm being too big unless you have large work. ARC have a good range, and they also show the footprint if their products, you can cut out a piece of cardboard to lay on the mill bed to compare sizes.

10/08/2021 15:42:22

That antirotation screw on the museum's Taiwanese round column drill mill is unusual in that it's thread is either Whitworth or UNC, not metric.

I notice that your spindle is Morse taper and there is an extraction slot for when larger drills are fitted directly to the spindle. That will prevent overpacking with grease alright. laugh

Edited By old mart on 10/08/2021 15:45:59

Thread: chinese lathe tailstock is 3/16" too high
10/08/2021 15:36:11

There will be a joint between the base and the top half, this is where the 3/16" would be best removed from. This would be easy if a mill was available. The alternative might be to mount the base on a faceplate, square up the surface and turn off the surplace.

The tailstock of the museum Smart & Brown has shims between the halves to get the height and direction of the quill on the centre line. Actually it is set 0.001" high on purpose. I ought to set it up and mill it to take a decent thickness shim, but I'm too lazy.

On the other side of the pond, The Home Shop Machinist forum is well worth joining.

Thread: Unusual Go-No Go Tool?
09/08/2021 20:31:57

It is obviously made to fit in a coat pocket along with pens. What happens at the buisiness end when the scale is moved?

Thread: Dipping a toe in TIG - what do I need (apart from skill)?
09/08/2021 19:15:14

I was told that the more sophisticated kit with the foot pedal was worth the extra money.

Thread: What are these tools?
09/08/2021 17:36:38

I used to have one of those drill grinding attachments fitted to the bench just to the left of the grinder. The grinder in the picture, being right handed and not double ended would have difficulties mounting. When I sold my house, I left the grinder, drill sharpener and a 4" Paramo vise bolted to the bench. I miss the vise.

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