Member postings for old mart

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

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.

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

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

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

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

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.

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

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.

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.

Here are our efforts at engraving the scales for the lathe:

My advice to anyone thinking about replacing their lathe spindle bearings is to buy the new bearings, and make the tooling to reassemble the bearings without stressing them before taking the thing to bits. Aluminium rings which are a loose fit in in the bores and on the shafts, which press on both inner and outer races at the same time, and tubes if necessary to push with.

None of those holders are too hard to file, but they are not far off.

I bought one of these to utilise the large propane cylinders, it comes with the left hand threaded bottle connector. Later, I got one of the American style "ACME" bottle connectors which fit the propane bottles fitted to fork lift trucks. It is not really hot enough for largescale brazing, but is useful for general heating and is much cheaper to run than my MAPP torch.

**LINK**

For smaller scale silver soldering and brazing, I can recommend one of the MAPP gas torches.

Edited By old mart on 10/09/2019 22:57:28

I have a couple of dozen 20mm toolholders of many different shapes for the museums Smart & Brown model A. They are all milled down to 17.53mm to go in the toolpost without bothering about shims. I use a 50mm 5 insert Ceratizit shell mill with RPHX12 round inserts. I have a lot of inserts for this shell mill and they either index in 4 or 8 places. Milling down any of the toolholders is very hard on the inserts, with one or two indexes required for each. I can definitely say that the very cheap Chinese holders are just as hard to mill down as the Sandvik, Korloy, Stellram, Iscar, Tungalloy, Kennametal, Seco, to name those that I can think of at the minute. I buy them all on Ebay, and certainly would never pay more than £18, even for the big names. This is the main reason I have never contemplated getting a QCTP.

I make some toolholders for the more obscure insert shapes, along with parting blade holders, boring and threading insert bars.

 Carbide shims are good to save damage to the toolholder if there is a big crash. The cheap shims available from China are not carbide, they are steel.

Edited By old mart on 10/09/2019 22:27:13

You will be spared the frustration of having to manage milling on the lathe, which can be extreme. Having a shortage of space can sometimes be mitigated by devious thinking, such as having the mill on a piece of 1" thick plywood on the bench, which can be fastened down for milling, and then moved aside to make more space when the mill is not in use.

 I've had a look at the mill mentioned, and it looks good, especially the R8 spindle taper.

Edited By old mart on 10/09/2019 17:45:36

My next door neighbour has a Harley Davidson with a standard factory exhaust that wakes up the street when he starts it. They must be special, every other manufacturer has to fit silencers to their bikes.

I bought a brand new Villiers Starmaker scrambles engine from P & C shortly after Villiers went bust for £80, complete with 1 3/16" Monoblock.

With a mill and rotary table, that sort of engraving can be done. We did two, one with 118 divisions and numbers every ten, and another with 125 divisions and also numbers every ten. They are fitted to the lathe cross slide and the tailstock. A jig was required to hold the punches for the numbers. We took the easy option and made them out of aluminium.

If I remember, I will take pictures of the engraver. It is a simple push type using the quill, I tried rotary tips with unusable results.

The difficulty is not just the adhesive being weather proof, but the flexibility required.