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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: Power cross feed: electric motor or linkage to spindle?
14/09/2019 20:47:19

You could do without a powered cross slide, but getting the saddle connected to the leadscrew is important, but usually only needs the leadscrew nut/s to be working. The gears that move the saddle along the rack are important. The gears that power the leadscrew which live at the left hand end of the lathe are frequently missing, but are easier to replace. I have removed all the hard to get change gears on the Smart & Brown Model A with similar size easy to obtain mod 1 metric gears. This is possible because at the left end of the lathe, the gear spacing is adjustable to accommodate different tooth counts.

Thread: drillling bronze
14/09/2019 19:17:00

Blowlamp, your drill on the left is a split point, not a special brass/ bronze one. The relief angle is the same as the one on the right.

14/09/2019 19:13:40

_igp2455.jpgI have a couple of pictures of a drill bit that has been backed off, it needs sharpening.

_igp2453.jpg

Thread: ACME thread identification question.
14/09/2019 18:58:08

Thread rolling is a specialised process, which most firms would sub out to the experts.

Thread: Solvent for degreasing engine, without damaging the paintwork?
14/09/2019 18:53:28

Jizer or Gunk are water washable degreasers which are unlikely to damage paint.

Thread: MT2 or ISO30
14/09/2019 18:50:57

ISO 30 is a proper milling spindle size, Morse tapers were designed for drilling machines.

Thread: drillling bronze
13/09/2019 20:28:47

I will try to remember to take a photo of a drill tip which has been backed off, tomorrow.

Thread: ACME thread identification question.
13/09/2019 16:24:21

There is a UK company selling metric leadscrews and nuts, but not in 2.5mm pitch:

**LINK**

 I have looked everywhere for 2.5mm pitch trapezoidal, and cannot find any, funny as your Boxford is not alone, the drill mill at the museum uses 2.5mm pitch screws on the X and Y table travel, although they are much larger diameter than yours.

Edited By old mart on 13/09/2019 16:34:30

13/09/2019 15:55:28

If all else fails, just get a 12 X 3 trapezoidal leadscrew and nut and graft it onto one of your existing ones?

**LINK**

13/09/2019 15:33:59

You said you had another leadscrew and nut, could they be used?

Thread: drillling bronze
13/09/2019 15:31:23

I have drilled various grades, and treat it like leaded brass, which tries to grab the drill. With larger drills, it is easy to stroke a stone across the cutting edges to reduce the rake angle, but the small ones are difficult to do. Holding the drill in a vise and using a magnifying glass might work. The use of a mill with a slow feed on the quill is a huge advantage over the ordinary drill press. With a drill press, it helps if you can partially lock the quill, and use both hands to keep control of the feed rate, which should be as slow as you can manage. Just a drill on its own is not going to work unless the bit is really well backed off.

Thread: Are there any left?
12/09/2019 21:19:49

I stumbled upon a shop in Worthing, about 25 years ago and bought a couple of dozen potentiometers in the 10k and below range, probably for controlling computer cooling fans. They had all sorts of obscure electronic stuff. They also had some target rifle parts, I bought a handstop to fit in a fore end rail, it is still on my Gamo 126.

When I was a kid, my uncle gave me a gunsight from a 25 pounder which he bought in the lanes in Brighton, probably all antique shops and coffee bars now.

Edited By old mart on 12/09/2019 21:22:59

Thread: Engraving
12/09/2019 20:53:10

You're right, Jason, it is indeed VCGT 160401, that is tiny. I tried them on the lathe, but with their tiny rads, I haven't found a use for them. I also have others with much bigger rads which are more versatile.

 My Carbide Depot insert designation chart doesn't list that "01". 

 

 

Edited By old mart on 12/09/2019 21:02:19

Thread: Start of Tom Senior refurbishment.
12/09/2019 20:30:56

The digital quill depth reader has been finished, I had to cut about 1/2" off one end and it was more of a challenge than I thought it would be. It wore out two new Eclipse junior hacksaw blades, and then I thought it would be a good idea to drill a hole in the bottom end. I used a new solid carbide 7.3mm YG Dream for hardsteel, it did the job, but any hss or even cobalt would have failed completely. The aluminium block in the picture looks a lot different now. The stroke of the quill is exactly 2.5". Mike made a nice cap for the projecting end of the drawbar out of two pieces of aluminium fitted together as we couldn't find anything to make it out of one piece.

The motor will have to come off and be turned round, as the wiring box comes very close to the bracing for the mezzanine, especially if the head is tilted.

Edited By old mart on 12/09/2019 20:35:02

Edited By old mart on 12/09/2019 20:43:38

Thread: Engraving
12/09/2019 20:01:54

Aluminium is much easier to work with than steel, including the straight knurling on the lathe cross slide wheel. As for the jig, it only does one size and to avoid the variations in depth of the punch marks, it is preferable to do all the stamping exactly on the centre line. This would need some marks on the jig to space the numbers each side of the engraved lines equally. Doing test stamp placings on a flat piece of metal and measuring the pitch of the most visually pleasing pairs would be the best method. Two marks for double numbers, and three different marks for single and triple numbers. The stamping on the cross slide wheel was done using the jig, and the tailstock was freehand, and it shows.

As in the video, there are long curled burrs left as the tip cuts, I found that brushing them with a brass wire brush gets rid of them quite well (real brass, not brass plated steel). The aluminium needs to be a hard alloy, not soft pure stuff.

Edited By old mart on 12/09/2019 20:11:47

Thread: Degreasing
11/09/2019 21:26:19

If you only have one chuck, make sure it is a four jaw independent. More versatile and capable of holding the work more securely and running more accurately. Practice is all you need, the professionals running manual lathes are much more likely to use them, and make it look easy.

Thread: Why are insert toolholders so expensive?
11/09/2019 21:07:54

The holders that I have made are mainly key steel, but I have sometimes cut the handle ends off those old fashioned thread chasers. Having bought job lots of carbide inserts and ended up with some weird and wonderful types which defy identification amongst the common ones, I have some very odd tools in the collection. Some of the really big inserts make excellent scrapers screwed on to handles.

 Dead right about the prices industry is prepared to pay, Neil, If I want something that I can't get on ebay, Cutwel and APT will probably have it and you get it extremely quickly, but cost a bit more. Normally, I don't mind waiting 10 or more days for China Post, but not many companies could afford to wait that long.

Edited By old mart on 11/09/2019 21:18:08

Thread: O rings.
11/09/2019 20:58:29

Most of the sizes are available on ebay, I believe the dimensions are inside diameter and diameter of the rubber. I have bought nitrile, EDPM and viton o rings. Recently, I bought a metre of 7mm nitrile to make a buffer stop for a mill quill, and had to buy the correct type of super glue when the stuff I had would not glue it.

Thread: Engraving
11/09/2019 20:49:15

As usual, the text which is written first, ends up stuffed in the middle of the photos which appear in the opposite order that they were added.

The inserts have VCGT 1604 printed on the box, but I think the tip rads are much smaller. You would have to use a magnifying glass to see that there is a rad, and not a sharp point. If using a rotary table to do the engraving, it would be important to get the work running with absolute minimum radial runout. I had to lock the mill spindle from rotation, as the slightest movement would ruin the spacing. I couldn't do anything about the backlash between the quill splines and the pulley which was locked, but luck was on my side that day. For the 118 graduations, the RT had to be set to degrees and minutes. Keeping concentration while cutting the three lengths of line was too much for me and there are a couple of mistakes on each scale.

11/09/2019 20:26:09

_igp2449.jpg_igp2448.jpg_igp2447.jpg_igp2446.jpgHere are our efforts at engraving the scales for the lathe:

_igp2445.jpg

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