Member postings for Pete Rimmer

Hi Drew,

Have you searched on the Denford forum, they have a novamill section **LINK**

Pete.

That would be a very rare occurrance. We use SY at work to power fully mobile demolition plant in and over the last 25yrs I've seen it smashed, squashed, crushed, sheared in two and torn clean out of the plugs and sockets many, many times but I've never see the braid forced through into the conductor without it being completely flattened under a steel track or accidentally caught by a clumsy operator.

Actually SY cable should not utilise the braid as earth protection:

https://www.voltimum.co.uk/content/earthing-cable

Yes there is a problem wit SY not complying with BS-something or other. Have no fear though it is plenty good enough for power supplies we have been using it up to 100A for our mobile plant at work now for at least 25 years, all in extreme duty situations. It's very robust.

Only just recently have we had an issue with a main contractor insisting we use HO7RN cables instead of SY, and that was only because of an audit.

Red Black Blue went out more than 15 years ago. Now it's Brown Black Grey.

I'd replace those if I could, but it wouldn't bother me if I couldn't and if running a tenth-reading dial across the marks showed no flicker of movement in the needle.

Most of the hobby-grade milling machines out there have much less than perfect bearings.

I use Plant Net on my phone it has a high accuracy rate from what I can tell.

Bazyle yes they are all nose-heavy. I have them retained with a thumbscrew from below.

Slips are unlikely to be out by any measurable amount. If they are still shiny, they will very likely be good. If you really wanted to be anal then do the check twice or thrice with different sizes of slip. The chances that several slips will all be worn by a similar amount are infinitesimal.

Excellent handy storage Mark. No point tearing your back out lifting parts that can be stored at a handy height for direct mounting.

I have done something similar for the TOS mill I am rebuilding. It has swappable tables and work heads which are all 30-50KG so I have mounted them all on a wall rack and I've made a small swing crane to load them on and off the machine when it's done.

Dial gauges are the easiest thing in the world to check for reading accuracy. Pass a slip under the stylus or anvil, record the reading, pass another slightly different thickness slip under it. If the dial records the difference accurately the instrument is reading correct.

Rowan, as Chris Evans said your choice of material is not great. 304 stainless is an awful choice for a novice to machine.

Does the part particularaly need to be stainless or is it just that you happened to have some so decided to use it?

Steve, looking at this video:

*LINK*

Since you are measuring directly over the vee block this should be showing no runout. Possible causes are:

• Bearing diameter out of round
• Burr or ding on the egde of the bearing register causing it to ride up on the vee block. You can eliminate this by putting slip gauges in the vee blocks to raise the spindle off the wider vee so it doesn't get affcted by any edge ding.
• Bent spindle
• Top bearing register not concentric with bottom bearing register, or it has a ding/burr.

Another good check you could do is put the vee block under the chuck register then use your DTI to check the taper and the bearing register. If the taper runs true but the bearing register does not, one solution could be to knurl the register to raise the diameter a bit then turn or grind it back down to the bearing diameter, whilst supporting the spindle in a lathe between a 4-jaw and a fixed steady on the chuck register. It won't be perfect but it'll get your TIR down to a couple of tenths rather than a couple of thou.

Yes the pear shaped stylus is designed to reduce cosine error but it won't prevent the over-reading error that Steve's setup would incur.

DTI's and plunger-style dial indicators can both act as comparators and both take direct measurements.

One of the most common mistakes made whilst taking direct measurents with a DTI is the one shown in Steve's video (sorry Steve) where the lever is not tangential (or parallel, if it's a flat surface) to the work. Steve's is a particularly good example because the lever is so far from tangential the cosine error will be large. In the video it is showing 3 thou TIR but if the DTI were moved down so the stylus was parallel to the floor that reading would probably be less than 0.002".

Other things which can cause false readings are:

Using the instrument held rotated in the holder so that the lever is not swinging perpendicular to the axis of the shaft being rotated. Always make sure the instument is held perpendicular to the part.

Using the instrument with a different length stylus than it was designed to use. Fit a longer stylus, it will under-read. A shorter one will over-read.

Plunger type dial gauges will also over-read if the stem is not perpendicular to the work, though the error is usually very small. If you're taking runout measurements as in the video it must also be reading on the centreline of the part, to again avoid cosine errors.

I am having mine skimmed but it is a 90-degree angle table with stiffening webs. I would worry about skimming a flat table lest it release stresses and bend somewhat. A lot depends on how well it was stress-relieved during production.

Here's a vid I made of a builder's level, a 10 second level and a 5 second level.

https://www.dropbox.com/s/nzcfyqn9quz1lvx/levels.mp4?dl=0

Here's another part. Obviously it's an 8-postion stop but can anyone identify the purpose? i'm guessing it's milling machine or capstan lathe.

Anyone recognise it?

Can anyone identify this attachment please?

I expect it's a part from a T&C grinder or similar. It has a 5/16" collet frozen into the end. The locking lever prevents the collet sleeve from turning otherwis it's free to rotate. I suspect that the knurled wheel on the rear is what pulls the collet in but I cannot be sure.

Pics below or you can view the album for full size ones.

Thanks

Pete.

The easiest way to make male dovetails co-planar is to scrape the female one first on a surface plate and use it as a gauge. You still need a straight edge because most female dovetails are shorter than the male but between that and a mating part that you have scraped you have all you need to match two flat ways either side of a dovetail.

Obviously doesn't work where a female dovetail rides on the internal ways which is thankfully not common.

Edited By Pete Rimmer on 27/08/2022 09:16:44