Member postings for Martin Connelly

Had a look on the lathes site to see what these were. I noted that it stated they were well made - then saw the stamping on the name plate and thought it looked like it had been done by the newest apprentice doing it in a hurry in a bit of spare time. It does not look good on a potentially expensive part.

Martin C

I run XP on my W10 laptop using VMware virtual machine to use my Cannoscan scanner that also will not work directly in W10. I have a folder that is shared by W10 and the virtual machine to swap files between the two systems.

Martin C

The TPI/pitch of the threads often gives a good idea of what it is. If you do not have thread gauges to measure this then estimating against both metric and imperial scales can help.

Martin c

I found somewhere a figure for the minimum diameter of the thread being cut compared to the diameter of the cutting tool for straight threading tools with no helix angle. I think the tool had to be 60% of the thread diameter to ensure the thread was not overcut due to the tool helix angle (0° ) being different to the thread helix, the thread helix angle reducing as diameter increased. This means that if, for example, you wanted to make a 1mm pitch thread from a Ø6mm thread milling cutter the thread being produced would have to be 10mm diameter at least. A play with 3D CAD would confirm if this is the correct percentage. For purchased single pitch cutters I think the manufacturers will have a data sheet stating the limits of what can be done with each tool. I have also used a manufacturer's web site (Vargus) to create G code for one of their cutters, put in your parameters and it will either say no way or produce G code.

When you make a tool from a tap there is the added problem that the tap is at a fixed helix angle and the material behind the cutting edge is not necessarily going to have the same back clearance as a tool manufactured for the job. You would have to remove a fair amount of material from behind the cutting edge to ensure there was sufficient clearance or only use it on quite large diameters to ensure there was no rubbing or overcutting of the thread. Once again 3D CAD could be used to check for interference.

Martin C

Smiley removed

Edited By Martin Connelly on 13/05/2023 12:59:03

Could be a dodgy floppy. Have you tried formatting another one? Have you got another drive to use to confirm that the drive is really not the problem? A USB 3.5" floppy drive for example? It would probably be a good idea to have one anyway if you are still working with these older systems.

Martin C

If you have a mill and a rotary table making one should be easy as well. Possibly why they are hard to find commercially.

Martin C

The default numbers I put into the zip version were the same as the default numbers in the HTML version. So I imagine it is basically the same underlying program. Try using the HTML defaults and see if you get the same results.

Martin C

Just noticed that further down on the HTML version it says it is based on the flywheel.c program that is in the zip file.

Edited By Martin Connelly on 11/05/2023 23:22:21

As a starting point:

Is the threaded rod a metric M12 threaded rod? if so what is the pitch on the 12mm rod? If it is standard 1.75mm, at 1000rpm you are going to be moving the tool at 1750mm/min. Is this the travel rate you are after?

What is the threaded rod made of? Stainless steel, brass, mild steel, hot dip galvanised steel or something else?

How straight is the threaded rod? What bearings is it running in? What is it driving, a standard nut or something else?

Is it a ball screw and ball nut?

What weight is being moved by the threaded rod?

What is the moving part running on? Smooth surfaces? Bearings? Something else?

Have you tried turning the rod by hand to see what effort is required to turn it?

The answers to these questions will give a starting point to work from to see if we can help you.

Martin C

I ran the flywheel program in Dosbox. It produced a text file with a .out extension. Here is a sample from it.

The rotary table settings (deg) for the inner holes are:
30.000
90.000
150.000
210.000
270.000
330.000

The rotary table settings (deg) for the outer holes are:
7.000
53.000
67.000
113.000
127.000
173.000
187.000
233.000
247.000
293.000
307.000
353.000

Martin C

It looks like it may just need knocking out from behind (below in the picture orientation), the slot looks like it may be tapered. A key like that will get some wear and tear in regular use so it should be a simple job to replace it.

Martin C

Once you have done a few steam engines they can become un-interesting as it is, to some extent, repeating what you have already done. I keep my interest in machining going by making parts to drawings for the UK Monowheel team where each item is a new challenge to make something I have not done before. I enjoy the pre-machining work planning as much as the actual metal cutting part. Some of the parts are at the size limits of what I can do which creates a challenge in itself. There is variety in the materials used as well. When the part is made I pass it on so I do not get cluttered with such objects. My fill in between these outside jobs is Elmer's wooden grasshopper which I can pick up again and do something and then put to one side for another day. It's interesting doing something in wood for a change.

Martin C

I would just point out that the gauge pictured would not have been allowed to be used for pressure testing or on gas equipment where I worked. You were not allowed to use gauges with a hard stop at zero as you could not tell if the gauge was reading zero when depressurised, it may still have pressure in it even when reading zero. Also the hard stop could knock the pointer needle around on its spindle resulting in inaccurate readings. If you get a replacement aim to avoid such gauges for something used with flammable gasses.

Martin C

Frances, shouldn't you have a capital letter at the start of a sentence and maybe a pronoun before the verb? Possibly a couple of commas could be used to separate the clauses?

Martin C

5C collets have an internal thread so they can be fitted with a depth stop. ER do not and neither do any of my lathe specific collets or R8 collets. I'm sure if it was felt necessary someone could design a workaround for a depth stop but there are usually other alternatives for a one off requirement. The Clarkson collets (as mentioned by NDIY) go into a chuck with a centre that acts as a depth stop but they are not designed for work holding, only milling tooling with the necessary thread on them.

I usually use a Clarkson style Vertex chuck for milling tool holding but sometimes use R8 or ER. I also sometimes use ER in the lathe tailstock and lathe specific in the lathe spindle. I have a spin indexer that is 5C but has an ER adaptor but I do have a few 5C collets for it that are larger than ER32 sizes but rarely use them. I have square and hex collet blocks for the lathe collets.

If you get ER collets and a square collet block you can hold something tightly then put the collet block in a 4 jaw lathe chuck and dial it in to an acceptable runout regardless of the collet's quality. Then transfer to another machine if required with it still in the collet block. So don't worry too much about such things as runout with ER collets until you have a real problem that can only be solved with super accurate collets and collet chucks.

Martin C

I have renamed the freshly installed directory something like Mach3fresh then copied the folder from the defunct computer to the new computer's drive C. That way if there is a corrupt file or two in the older version you have something to replace it with from the fresh install. I also regularly copy the working Mach3 folder onto something other than the working hard drive to preserve any changes that have been made in case the working folder gets scrambled. It doesn't take much space up on a USB stick. The thought of having to reconfigure everything from scratch is worrisome.

Most recently I copied the folder onto a different machine as the old one was starting to play up, dodgy USB ports on the motherboard was one problem it had. It caused no issues to just copy everything onto a new drive that had had a fresh install carried out on it first.

Martin C

Don't forget that the maximum pressure differential between a vacuum and atmospheric pressure is less than 15psi and slightly more than 1 bar. Compare this to compressed air at maybe 75psi, steam at 200psi or hydraulics at 3000psi and you should appreciate that holding a vacuum is not an arduous task for most fittings.

Martin C

I used to get pipe data as a coordinate table on a drawing, use the coordinates to put the shape into 3D CAD, fillet the bends to the correct radius then sweep a circle along each line segment. I was then able to test if it could be manufactured as drawn by putting into a 3D model of the CNC pipe bender's head. and checking any dodgy bends that looked like they would cause the part to clash with the machine.

Martin C

Had a look through this thread for the first time today. Couldn't see any mention of this. It is not usual to put a round rod in the mill and move it up and down as any out of tram will result in the DTI giving unpredictable readings as it moves around the curved surface. As a result I advise you do what is more usual. Put the DTI in the spindle and move it over a vertical plane surface (angle plate or 123 blocks for example) on the mill table. Rotate the vertical surface 180° and repeat in case the surface is not perfectly vertical. Average out the two readings unless they are the same.

Martin C

Here are a couple of collet options.

Stick an ER collet chuck in a 4 jaw independent chuck and get it running as true as you want. Smaller ones can be bought with a Ø16 parallel shank, you can go up to ER32 with a Ø32 shank. A cheap stop gap as you build up a collection of the real ones using Martin K's method. The disadvantage is that some of these parallel shanks do not have a through hole. They may also require shortening to get them sticking out as little as possible (not too hard to do with an angle grinder if the shank is hardened) if you get a shank larger than the spindle bore.

Buy a backplate and ER front plate to make a collet chuck that replaces the standard chuck when required. This has been done by plenty of lathe owners.

Parting off (or grooving) using a collet in the spindle nose is always easier than something sticking out a long way either in a chuck or collet mounted anywhere other than one in the spindle. It's just the way the mechanics of parting off works. This is a good reason to aim for the real thing.

Martin C

Prismatic may only need one adjustment to keep the saddle smooth without being too loose, flat top and sides requires two adjustments for carriage lift and carriage rotation. Don't know if this is the only advantage.

Martin C