Myford super 7 Positioning servo's on Spindle and main infeed

Have to agree with Martin, it looks like they have left the corners 'sharp' as well, they will wear poorly. You'll probably have to relieve the internal corners of the saddle and tailstock casting as well.

If you look at a factory fresh bed the chamfer is considerable.

Spindle mounted, I now need to investigate if it needs new bearings,

Edited By Andrew Davies 4 on 03/10/2018 16:04:20

Hi

Yes they did the feet first and the undersides (picks on request) , the only faces they did not do where the inner vertical and the inner underside. I do not think this will be a problem.

Can I ask what you think the problem is so I can look into it further? I have clocked all edges and they are fine.

It is easy to be negative from a distance, but constructive input would be better, crappy does not help. 

Andrew

Edited By Andrew Davies 4 on 03/10/2018 16:01:49

Edited By Andrew Davies 4 on 03/10/2018 16:06:21

Edited By Andrew Davies 4 on 03/10/2018 16:07:32

Happy to go over the grind corners with a stone.

Edited By Andrew Davies 4 on 03/10/2018 16:06:43

Edited By Andrew Davies 4 on 03/10/2018 16:07:59

Time is important to me, so the fewer the words the better. Crappy is how it looks in the pic and you didn't grind it so please don't take offence.

It looks like it was ground with a blunt wheel or there is a duff bearing on the wheelhead of the grinding machine or something.

The inner/front vertical shear (usually) guides the saddle and so needs to be in good order to work properly.

The guiding surfaces of the saddle are also usually remachined and then scraped to match the newly reground bed. Was this also done?

I think the corners will require a LOT of stone work to get a good enough chamfer. The inner shears not being done mean you'll have to do a wide guide conversion if not already, saddle will need a bit of work on all surfaces.

Tailstock allignment will need work as well.

Hi

Had a little time to think about this. I now understand the need for a chamfer.

With regard to the saddle, I was going to blue it up and use the bed to show high spots and scrape. Looking at the saddle, you are correct; it does use the inner front edge, this I will need to sort. As this is the only face without adjustment, this must be the datum. Does the back outer face do anything?

Are the two bottom plates ground to the correct size or is tighten the bolts that hold them all that is needed

As the bed is now narrower than before, will the adjustment screws not take care of this?

I think the solution is to get the bed back on the grinder to sort out the chamfer and inner edges.

This electrical engineer is learning a lot quickly! This was always going to be a learning process, I am sure I will have to rectify a few more mistakes before I am finished.

Many thanks for all your input

If the lathe is a narrow guide machine, then you are correct – the smaller face is the datum and the rear face does nothing. However, I would do a ‘wide guide conversion’. This means that the smaller inner shear does not contact the bed at all and instead the saddle runs on the much larger rear shear as the datum and front gib for adjustment.

The two saddle strips will probably require work (I refinished mine on my shaper) but if you have access to a grinder it would be nice to do. They amount of saddle lift allowed by these plates is controlled by shims which are fitted between the plates and saddle casting.

I would also get the bearing surfaces of the saddle ground – but make sure they set the saddle up correctly in relation to the cross-slide dovetails. Having the inner shears ground is necessary if you intend to use your tailstock!

As for the bed being narrower because of the regrind – yes, the gib adjustment should allow for this, if they haven’t removed too much. Did the grinders not tell you how much they removed? What you’re probably going to struggle with as well is half nut/ lead screw alignment as the saddle will be sitting lower than before. The other option is to have the saddle ground and then have turcite fitted to bring the saddle back to its original location – to do this the grinders need to remove a specific amount depending on the grade of turcite you intend to fit (it is available in different thicknesses).

As for the bearings – if the front bearing has not been starved of oil the chances are that it will be perfectly serviceable. Replacing the rear bearings is a very easy thing to do, whilst you have the machine apart I would replace the front bearing wick and clean out the oilways in the head as well. You could of course re-scrape the front bearing if you wish.

Plenty to think about! Just be methodical!

OK

I have spent time this morning looking and thinking about the feedback.

I am going to finish the corners that are a problem (not all of them are as they are not used.) with a dremel, not the perfect aesthetics but will be OK, I will take my time.

I have put the saddle on the bed, I think I can compensate for the grinding with shim. I have tried the saddle on the bed and running smooth without movement using bits of shim as a test.

I am going to clock it up when I have purchased a selection of shim strips.

What sort of tolerance should I be looking for; bearing in mind this is a hobby lathe?

All the best

Andrew

Yes, good point. the electronics and controller software don't come cheap, nor do they wire themselves up magically.

No idea how many (if any) they have sold but if course, if you don't ask you don't get....

Murrat

Thank you Nick, your input is great. I will look at a wide guide conversion.

With regard to the electrics, this I know a lot about and can do no problem.

I retired through ill health earlier in the year at 56. I get my driving license back in Feb 2019, this is filling my time and is great fun. Start working part time next year.

Andrew

Hi Nick

Just looked at the wide guide conversion, this make total sense and very easy to do. I will do this.

Many thanks

Andrew

A question

How do I stop the new shim on the rear vertical slide moving on the conversion. I have seen a person using super glue. is this a real solution?

Would I use carbon steel or brass shim?

Andrew

Hi Andrew, I would use epoxy and some gauge plate (pre-ground) I think Radford (original inventor of the idea) called for 3/32" thickness (just under 2.5mm) but don't recall exactly.

Not sure if Radford's write up is available anyway.

.

It's in his book:

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=130088

MichaelG.

Servo motor mounted for ball screw, and bearing mounts and nut mounts fitted. Fitted shim and now using the two out sides of the bed. Designed main spindle motor mount and worked out the two pulley ratios required and identified components and keyless couplings.

Added more photos to my album.

Myford super 7 upgrade

Hi

Come on a long way since last post.

Added photos to Album.

Ball screw fitted, controls nearly sorted and spindle motor mounted.

Happy Christamas to all

Andrew