Member postings for old mart

That is a good design to use with standard jaws, Dave. I suggest you drill and tap at least 2 more locking holes, up to 6 if you want, so the jaws can be rotated when the first position gets used up.

About 50 years ago, the catgut in our grandfather clock failed with old age and I replaced both the clock and the chimes cord with that white string that butchers used to tie up joints.

It looks like somebody had a set of the collets and made a closer with the correct angle to enable them to be used on a Smart & Brown lathe. A drawbar to suit the spindle and collet threads together with an adaptor to fit in the spindle to keep the collets centralised. The closer would not be guaranteed to keep the collets aligned on its own.

Measure the thread on the end of the collet, if it is 0.902" x 24 tpi W is will be the 2804 type used on the Smart & Brown model A and some model M's and L's.

Your collet threads would seem to be much smaller, but the closer looks exactly like the model A one we have.

Edited By old mart on 06/08/2022 21:24:29

The bed, and head are now fitted, and I got the head trammed in only 30 minutes, despite the design made especially to make tramming difficult. Now only the motor remains unfitted.

While the Tom Senior is in bits, I decided to make the Yaxis nut backlash adjustable without didmantling the machine. The pictures show my way of doing it and Mike and myself did some turning, hacksawing and milling to make a tool that can reach under the Y axis.

My 7 x 12 needed a new speed control pot/switch many years ago and I got the pot/switch from Maplins. I had to reverse the switch action because it was off to on when it needed to be on to off. The proper switches can be obtained from ARC.

The stickout length would be the same with the similar type I use, but mine are 20mm, so the stiffness would be better. The design having a double ended insert makes that type rather long which is unavoidable.

Power crossfeed does help a lot, and makes it easy to apply constant coolant, too.

There may be a small improvment, I filled the car up from nearly empty and the bill was £12 less than I expected for 44 litres of diesel.

As Mark Rand says, carbide parting off should be above centre height. I have read the instructions from Kyocera and Kennametal and both state that the tip should be 0.1mm, 0.004" high when parting solid stock.

I never part with anything but carbide inserts and have never seen two streams of swarf coming off. The profile of the tip makes the ribbon curve longitudinally like a length of rainwater gutter which is then narrower than the width of the cut.

Any loosness in gibs or flexibility make parting much more difficult. I have a solid block with inverted blades which bolts directly to the cross slide and together with front and rear saddle locks, is used for the most challenging parting.

A four jaw independent chuck and the minimum work overhang also help.

Edited By old mart on 03/08/2022 21:33:08

Edited By old mart on 03/08/2022 21:33:34

My Suzuki 400 Burgman has an 81mm water cooled cylinder and the top and second rings fitted gap is 0.002" to 0.008".

I hadn't seen a large screen digital caliper until this thread prompted me to google them.

**LINK**

1mm gap in a 2" bore would never close up, no matter how hot the piston and cylinder got.

That Myford picture by ega is exactly the design that I used for the brass jaws I described in an earlier post, made simply because I had a bit of hexagon brass stock laying about. The have not found a job yet.

All of the Helicoils we fitted to aluminium aircraft parts, (thousands) were cadmium plated stainless steel. They were fitted wet with compound, or occasionally wet epoxy primer to reduce water penetration. Titanium screws in aluminium would cause the aluminium to corrode even faster, check out the electro chemical series charts. Duralac would be easy to get hold of both for fitting any bush or insert type and also when the screws are fitted.

Good idea, Buffer, and there is room at the other end of those jaws for another three for outside use.

The screw in my shop made holder is displaced about 0.005" from the centre of the insert. This holds it tightly against the shoulder. With a close fit in the bore, it is essential to blow away the chips after every pass. The material the bar is made of is not steel.

I'm surprised you had trouble with cutter deflection with a solid carbide, normally they would break. A short series one would be a better choice if the work is only going to be 1/4" thick. I play safe and only cut about 1/6 of the cutter diameter depth per pass.

Just to show you what is possible with an unaltered 2.5 TR size 16 insert. The tool will pass through a 15.02mm bore and this one cancut 36mm length of thread.

Edited By old mart on 30/07/2022 17:28:24

Today, I decided to go for an even simpler option, just a clamp on the side of the nut. I am getting 0.004" backlash in the most worn centre of the leadscrew, and nothing either end of travel for the Y axis.

Edited By old mart on 30/07/2022 17:23:14

Edited By old mart on 30/07/2022 17:31:47