Member postings for geoff walker 1

Hi Bamber

Is your lathe bench mounted or is it on the Drummond stand.

If bench mounted the the duplex designed countershaft in the earlier message is a good design, not simple to make but if you have the time and facilities is well worth making. If you pm me I can let you have detailed drawings..

I assume your lathe uses flat belts, if so and the lathe is on the Drummond stand then the L H Sparey design is fairly easy to set up. You would need to get a copy of his book to see what the design is all about

If you have flat belts it easy to convert to vee belt drive but you would need to get the vee pulley parts from the later myford made m type

Geoff

Hi Martin,

Your mill looks good, enjoy it!!

Mine arrived yesterday as well.

Fresh out of the crate and after a quick inspection all looks good. It's heavy, I like that.

I was aware the mill has some "issues" e.g. the sprung arm to steady the head and the amount of play in the fine feed.

The first one, I may at some time replace the arm with a gas strut and the second, well I would like to add DRO's to the mill so that should resolve that issue. Not just yet though let's do some modelling first!

Geoff

Hi mick,

How about some more information? photos, suppliers.

Hi Gents,

Thank you for your replies and also, Mark, Martin, the advice and information.

All duly noted.

Geoff

I dont think you will be disappointed Geoff, as you have maybe seen from the start of this thread I have Martins ex SX2P, it is only 18 months old and like new. I am a beginner but already I can see it opening up all new horizons when it comes to model engineering. Enjoy it when it arrives.

I will Ron, I will.

I am planning to bench mount it but having seen the stand that is available from Arc I am having second thoughts. I'll see how it looks on the bench first.

Do you have the stand Ron? or anyone else?

Geoff

You will gather from the above I have a great regard for Arc, they are easy to do business with, normal disclaimer applies.

Hi Martin, couldn't agree more, every purchase of mine from ARC has been spot on in all respects.

I would imagine my purchase today, a Seig sx2p mill, will also meet those same standards.

Well I just had to have one!!!! My vertical slide days are over, at last, yipeeeee!!!!!!

Geoff

Hi All,

Has anyone any experience of using these. I thought about using them as main bearing inserts to carry the crankshaft on my new engine. Crankshaft would be 8mm dia mild steel or possibly silver steel. Engine will need to run at low and high speed Geoff

Edited By JasonB on 31/10/2018 13:26:02

A Jason says, increasing the lead helps engines run smoother on air.

Neil

....and he also suggests that adding lap may also make the engine run smoother on air.

It puzzled me why a model engine maker would add lap to the slide valve if they only intended to run the engine on compressed air.

Lap is used, as I understand it, to exploit the expansive properties of steam. Without lap a whole cylinderful of steam is used for each stroke of the piston. Adding lap, without going into detail, utilises the expansive properties of the steam resulting in the engine using less steam and thus being more efficient.

I think I can see what Jason is thinking, at high speeds and with considerable momentum does the engine need a whole cylinderful of air for each stroke?

Just my thoughts guys

Geoff

Hi Ian, Michael,

I do remain intrigued as to the original 'failure mode' though ...

It's not really a failure as such Michael. The unit is generally well designed the action is very smooth with very little backlash. The problem as I see it is the outer rim of the table has very thin section whereas the inner part of the table has a boss underneath which stiffens it up. If you look at the set up in the earlier photo you can see that the engine frame is bearing down hard on the outer rim. This combined with the upward thrust of the tee nut is causing the rim to flex, not much, but enough to create friction between the table and the base. It's a design fault, if the outer rim was a little thicker I don't think there would be problem.

Geoff

Hi All,

I have to say I was really disappointed with this little table of mine.

I didn't expect to have the problem I had. Having said that it was "cheap as chips" so I suppose you get what you pay for!!

Anyway I took Ian T's advice and made a small sub table. This is secured firmly by 4 screws nearer to the centre of the table. The underside of the sub table is relieved 3/4" in from the perimeter so no pressure is applied to the outer rim of the table.

No binding or flexing problems now and it should be ok for the work I have planned.

Geoff

Yes, nice work Gary, I've followed this thread from the beginning.

Well done but like others I would love to see an engine running.

I have everything I need to make a boiler except the inclination.

Having seen your success I really must get on with it!!!

Geoff

You should be writing that up David!

Neil

Sounds good to me I'll second that.

M.E. or M.E.W., I would imagine both editors would be very interested

Geoff

Hi All

Big thank you for all your replies, all of which are really helpful.

A little experiment last night revealed that clamping pressure on the outside of the rim causes the table to lock, when it's nearer the centre there is no problem. I set up a dial gauge as John suggested and you see the finger move as the table flexes, not much but enough to tighten it up. It's very frustrating, I'll have a good look at it this weekend.

Really like the idea of a sub table, I have one for my lathe cross slide, they are a good idea. It might help to even the load across the table

I'll report back on this one. Thanks to all again

Geoff

I recently bought a mini rotary table. see photos

Today I was milling a curve in the aperture of engine frame.

My problem is that with the set up I had when I tightened the nuts the table became very stiff and it was really difficult to turn the handle on the table.

As you can see i have brass tee nuts, 4mm thread, which accept 4mm studding. the bar which goes across the frame is 1/4" m.s.

The more I tightened the nuts the stiffer the table. It feels like the tightening is distorting the table and thus creating unwanted friction between the table and base. That to me is illogical but I'm stumped for any other answer.

Any thoughts Guys

Steve,

I have a potts milling spindle which I use a lot.

I had problems with spindle end play and solved it by removing one of the adjustment collars and replacing it with a slim thrust ball bearing (from simply bearings). The remaining collar is squeezed lightly on to the bearing ring and the end float is gone, completely. I locked the collar in place with small grub screws to retain the setting.

My potts has plain parallel bronze bearings.

Geoff

Hi Ross,

There is a forum on the chester machine tool site.

There is a post describing how a cooling fan is fitted to keep the motor cool.

Not your mill but might be worth a look

Geoff

Hi George,

I notice the pistons are bevelled. Never seen that before.

Presumably so that the piston will travel further and not cover the port hole.

....and you have that vee cut to aid compression.

Nice work Geoff

I need a 100mm dia flywheel for my next engine.

The one supplied by ATELIER looks more or less just what I need.

Could I ask does anyone have experience of Atelier flywheels, usual disclaimer of course.

It's not a cheap flywheel but I don't mind the cost as long as the product is good.

Any comments appreciated

Geoff

Nice work David, is it your own design?

Looking forward to seeing it completed.

A you tube video of it in use would be a good idea.

Geoff

Yes, very nice, as someone once said it's amazing what you find inside a big chunk of cast iron.

Hope you had a good clean up Brian!!!!

Geoff