Im just amazed at how big and how long these bits you guys are making.

On 25 June 2024 at 23:03 bernard towers Said:

Im just amazed at how big and how long these bits you guys are making.

Having bought two new lathes, a large spindle bore would be high up the list of wants if I ever bought another. Not only does it make larger parts easier and faster, but there’s less wastage of expensive material.

So do you think that putting a 500 mm length of 35mm steel bar into your lathe chuck a good idea, especially at 700 to 1000 rpm? Not sure your parts are going to be that round.

On 26 June 2024 at 08:14 bernard towers Said:

So do you think that putting a 500 mm length of 35mm steel bar into your lathe chuck a good idea, especially at 700 to 1000 rpm? Not sure your parts are going to be that round.

Is the 500mm sticking out of the chuck to be worked on? If so, who is going to machine it without a steady and/or live centre? If it isn’t and the required part is short, why would you waste time and a chunk of the material cutting it off a long length before working on it? 35mm isn’t a large or rare size for me.

I would have been a lot happier if I could have pushed this 3/4″ square bar back into the headstock instead of having barely enough room to machine the M20 threads on each end, especially as I didn’t have any more material:

On 26 June 2024 at 08:14 bernard towers Said:

So do you think that putting a 500 mm length of 35mm steel bar into your lathe chuck a good idea, especially at 700 to 1000 rpm? Not sure your parts are going to be that round.

You are assuming my comments about length also apply to dia of spindle bore. As for my lathe it is only 26mm bore so can’t stick 35mm up it anyway. I do have a couple of bungs for the far end to reduce whip on longer thin material.

But what I make seem to come out round enough as my engines run, many run without even fitting the piston rings, gaskets or seals yet make compression OK which I doubt they would if my pistons were oval.

I would think anyone building a 2″ or larger traction engine, 1/2 or 1/3rd scale hit and miss engines would find a use for 38mm bore spindle. As would many users who don’t even make models but may want to fit parts for bike or car restoration or modification. G1 locos you could get away with less, though could still come in handy to face off the ends of tube for gas tanks

If it is of any interest, I have been usinga generic Taiwanese lathe (Chester Craftsman, or Warco BH600, Engineers ToolRoom BL12 -24 – both the latter now discontinued) since 2003.

It is a lot heavier and more rigid than the ML7, with a 2MT spindle, that preceded it.

I have swung a 24″ lengths of 1″ bar in it without problems, (A 6 ” 3 jaw, or a 8″ 4 jaw chuck, are quite hefty items) so have to disagree with one naysayer.

The largest job?  Facing a 1″ thick cast iron disc, 6.125″ diameter, and then offset in the 4 jaw to bore a 1″ hole an inch in from the edge.

(With them curled around the shop, I have twice, carefully, turned fittings on the hose for pressure washers, to restore them to working order.)

Snallest job, thinning the heads of 10BA screws!

In my book, a very useful size of spindle bore (5MT, although mostly I use tooling no larger than 3MT)  and as Jason says, no collection of short ends to go to waste.

The spindle bore suggests that such a lathe is not small, by model engineering standards, verging on small industrial, aznd will be heavy and quite rigid. Mine weighs in at 300 Kg.

You can do small work in a big ;athe, but the reverse can be difficult.

FWIW, Go for it!

Howard

The gunsmithing guys over the pond use a more precision gunsmith’s lathe spindle spider on that end of the spindle to hold rifle barrels dead true when machining the chamber etc on the other end. Very handy. Just a collar that clamps on the end of the spindle with four adjustable bolts to hold the job. Simple to make and could be left in place permanently for use with long bits of stock etc.

On less precision jobs, I have seen old timers stuff rags into the spindle to stop a length of bar moving around too much.

The talk of gunsmithing reminds me of a police investigation that we had a few years ago where one of our mini-lathes had been used to lethalise weapons for criminal purposes. The fellow received a sentence of 25 years at Her Majesty’s Pleasure (now His Maj………of course)

Hugh                                                                                                                Amadeal Ltd

If it’s of any interest Artisan Makes on YouTube makes a spindle spider in his latest video – exactly to allow use of long bar stock sticking out the back.

Iain

I would have no problem with such a solution.

The demand for bigger bores has come with the need for higher speeds. There must be some limit to how fast a plain tapered bronze bearing can be run and, of course, the surface speed increases with the diameter. I think Myfords stuck with the plain bearing with their (not so) big bore machine.

Rik as you have been able to ask how here it looks like you have now got into the site OK