Member postings for geoff walker 1

Daniel,

In reply to your last post, no the roller bearing is not a replacement.

The caged ball bearing you have would be standard for your lathe, an early M type.

Davids mod is for the later M types 1925 to early 50's and not suitable for your machine.

The later M types had the improved main bearings with the thrust bearing at the rear but did suffer from end float of the spindle.

This can be mostly eliminated with the mod david suggests or an alternative approach by adding an additional thrust bearing at the left hand end of the spindle. The latter approach may be possible on your machine.

Geoff

Daniel,

Keith Robinson (52kr) currently has a some parts for sale on ebay.

Like David I have also bought parts of him.

Just keep your eye open on ebay plus other sites for spares.

Any problems you may have with restoration just let us know, there are a few guys on here with M types and we have all been through the restoration process.

Regards Geoff

Hi All,

No big deal this but as you guys were kind enough to offer advice I thought I would show the results.

I was surprised just how easy, by heating, it was to break the superglue joint between the cap and the boss.

Jobs a good 'un, thanks again Geoff

Hi All,

Many thanks for all your replies, very useful. Would have replied sooner but we had a tribal tsunami (aka the grand kids) last night so not much time for internet chat!

Yes I was thinking probably have to get it roughly round then bond the plate in place and as Rod said "creep up" on it and take by surprise.

Will use the tailstock for support. I like Davids idea of using a shallow counterbore.

I'll have a go in the week and report back

Big T again to all Geoff

Hi All,

I have a piece of BMS plate 1/8" thick and using it I want to make a cylinder end cap.

The cap needs to be 34mm O/dia and have a spigot 20mm dia and 1mm long to fit the cylinder bore.

Any ideas on how to hold and machine.

I have an idea but thought I would ask first to see if anyone has a better idea.

Thanks Geoff

Looks finished now David, except for the painting.

Assume the gears are ok, whole job very professional.

I used the grub screw method to hold it together while fitting the taper pin, GMTA?

Completed mine about 9 years ago, same patterns used for the castings as yours.

Here is an archive picture.

Geoff

Nice work David,

I admire your methods and attention to detail.

I suspect this will be the most accurate T.R. ever made!!!

atb Geoff

HI Pero,

New table, that's good news. Glad I was of help.

I've had mine nearly a year and have used it a lot.

It was only in the last month that I realised the main gear had 47 teeth.

If you remove the base it reveals the worm and gear arrangement and after several counts I finally accepted 47!!!!.

I'm looking to buy another larger one 4-5" diameter but this time will take advice first.

Geoff

Excellent work, nice castings!!!!!

Geoff

Hi Rod,

Nice set up that, I like what you have done.

You and Nick have also got me thinking. I have used this set up for years on my M type but now I have the seig mill I never use it.

With not too much trouble I guess I could retain the V/S, turn the potts through 90 degrees and mount the parvalux over the top.

We shall see, thanks to both for posting your work, very interesting.

Geoff

Hi All

I've Still got a few castings left if anyone is interested.

See the classifieds for details

Geoff

Hi Neil

My table has the cylinderical worm enveloping gear, very nicely made, all 47 teeth!!!!

Geoff

Posted by geoff walker 1 on 13/03/2019 09:23:31:

On accuracy this table is 7.5 degrees out over a full 360 degree rotation of the table. The hand wheel dial is indexed with 7.5 degrees and the hand wheel rotates exactly 47 times for one rotation of the table, should of course be 48.

LOL. Cost saving measure. One tooth saved on each worm gear means that every 47th gear they get one for free.

I bet you had some headaches until you worked that one out though. Who would think to check that?

Hi Pete,

Yes I did have some headaches!!!

When I first got this table I set the 0 on the circumference dial to the cursor and 0 on the hand wheel dial to the cursor, then turned the table through 360 degrees and much to my astonishment the dials lined up again. I thought WOW!!! that's accurate. Of course at the time I didn't realise that I was one turn short, 47 x 7.5 degrees and not 48.

The table has a cumulative error of 1.25 minutes per degree of revolution.

As I said in the original post I can still use table by making a coarse setting with the circum dial, which is accurately engraved and a fine setting with hand wheel dial. So for say 132 degrees turn 130 on the circum dial and 2 on the hand wheel dial. This gives me "theoretically" 132 degrees with an error of 2.5 minutes which is fine for what I do

Geoff

Or... Just accept it for what it is, a cheaply made bit of kit to provide an economical solution to the masses with a standard of accuracy commensurate with its cost. OP didn't state why he had bought it and what it's intended use is. If it's for the usual back yard engineering jobs like steam engines then bolt it on your machine and get using it. If it's for instrument making which requires extreme precision and formal calibration of the final product make sure your shop is kept at 20 degrees at all times, your measurement tools are only of the highest quality properly calibrated and buy a decent one. What else can be said? Seem to be a lot of people here chasing elusive microns where a couple of thou or in some cases 1/64" is perfectly adequate. Life and hence time allotted to us is finite so spend it getting on with the project and not chasing accuracy you don't really need! If you do need it don't buy your kit from purveyors of leisure grade equipment.

Paul.

I have read all of this thread with interest but particularly liked this post from Paul. Sums up My attitude!!

I bought this small rotary table from GDR some months ago and despite it having numerous faults it's ok for me and the standards I need to set when making my models. I've had to modify and improvise to make it usable but as I have said before it was "cheap as chips".

On accuracy this table is 7.5 degrees out over a full 360 degree rotation of the table. The hand wheel dial is indexed with 7.5 degrees and the hand wheel rotates exactly 47 times for one rotation of the table, should of course be 48.

I get round this by using the scale on the circumference of the table. For say 92 degrees I advance 90 degrees and then add 2 degrees from the hand wheel dial. that's accurate enough for me and the work I do

Cheers Geoff

Hi Bob,

For the reversing switch for the sx2p mini mill, google - Electronics- hacking the sx2 mini mill - that will get you the right page,

You will need a small on/on toggle switch, with 3 terminals, and a male plug to fit the spare socket on the circuit board. The plug I used was off an old r/c servo.

Read the article and you will see how simple it is to fit one.

Geoff

Hi Andrew,

Good point, Andrew, normally that would be the answer.

My problem was that with the home made fixture you see in the photo I can only access the gear blank from one side and that meant the spindle had to run in reverse.

Geoff

Hi All,

I've been gear cutting on the SX2P this weekend.

This machine continues to surprise me, I thought that the set up in the photo would be overloading the motor and it would labour when cutting the spaces.

Not so, with the spindle running at it's slowest practical speed, around 80 r.p.m. it "chomped" through the cast iron gear blanks. Admittedly easy machining stuff, like meehanite but still impressive for such a small machine. The whole machine steady as a rock.

I had to fit a reversing switch first as it was necessary to run the spindle in reverse. You can see the switch in the photo. for SX2P owners out there fitting the switch is really simple, with all the materials to hand about 15 minutes work. For details of how to fit one go to this web site http://tinyurl.com/hdbk36t

Geoff

Hi Adrian,

It's true what you say pattern making is a real art and very complex patterns are best left to the experts.

However simple pattern making is not that difficult but having said that you would need reasonably good woodworking skills and equipment. That is assuming you make them from wood with mahogany being a good choice for most patterns.

I would suggest you do some basic reading on sand casting and pattern making. An old school metalwork book would be a good choice, explains the processes but in a simple straightforward way.

If you do decide on a project do some simple sketches of your idea, post them on here a see what response you get. I've done a lot of pattern making so providing I don't miss your post I certainly will respond.

Good luck Geoff

Hi John

I used 120n on mine which easily supports the head and doesn't offer too much resistance

Geoff

Hi Jason,

Thanks for your reply. I thought about the pipes coming sideways but would prefer to have them exiting from the underside of the valve block then down through holes in the base into a hollow plinth where there will now be ample space for the pipework, to link the blocks. All the pipework will be concealed apart from a short inlet and exhaust pipe.

I am making the blocks muncaster style with two semi circular grooves as shown in the picture.

I really must open a build log on this engine, will do when I get back from holiday.

Thanks again Geoff