Worn saddle fix. Is this a bad idea?

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Worn saddle fix. Is this a bad idea?

This topic has 16 replies, 10 voices, and was last updated 2 March 2021 at 13:44 by peak4.

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1 March 2021 at 11:46 #10720
JDS
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@jds
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1 March 2021 at 11:46 #530942
JDS
Participant
@jds
The saddle on my 1971 S7 does not cut square when the gib's are adjusted up.

From reading up on here this is not uncommon and there is a fix by converting it to a wide guide. This involved machining back or off the shorter inner saddle guide so the saddle runs on the 2 outer most shears.

I have fixed this problem on my lathe without any machining work and it seams to work great so I am worried that I have missed something or I am going to damage the lathe.

All I did was loosen the gib screws off and insert two 0.4mm feeler gauge blades one on either side of the saddle in between the saddle and the and the rear most vertical sheer. Re tighten the gib screws and hey presto jobs a good un or so it would seam.

The only issue is that the feeler gauges can slip out but that is easily fixed.

My question is. Is this a bad idea? Can this increase ware on the shear more than the saddle running directly would. What have I missed.

This seams like such a simple solution and it seams to have worked, but any advice and guidance is much appreciated

Edited By JDS on 01/03/2021 11:47:32
1 March 2021 at 12:05 #530950
ega
Participant
@ega
Essentially, you have done what I did successfully some decades ago.

NB that you may need to re-adjust the apron to the saddle so that the half nuts are gripping the leadscrew correctly.

Edited By ega on 01/03/2021 12:06:06
1 March 2021 at 13:26 #530963
larry phelan 1
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@larryphelan1
Not much new under the Sun, is there ?
1 March 2021 at 13:48 #530964
ega
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@ega
Posted by larry phelan 1 on 01/03/2021 13:26:46:

Not much new under the Sun, is there ?

Agreed.

But was J A Radford the first to propose this kind of solution for the weakness of the Myford design?
1 March 2021 at 13:59 #530965
JDS
Participant
@jds
Hi thanks for the reply

That's good know it has worked for you and a good tip on the Half nuts cheers.

I have read the Radford solution but I don't have access to a mill.

Happy days that another job to tick off.

Thanks
1 March 2021 at 14:16 #530969
ega
Participant
@ega
PS See also Richard Gandertons' article in Home page reprints.
1 March 2021 at 17:57 #531012
Martin Dowing
Participant
@martindowing58466
I am aware that many people done what you describe, usually with success.

But why not to scrap back to shape original guide or/and a lathe shear as necessary?
1 March 2021 at 19:19 #531037
JDS
Participant
@jds
I did think about trying to but I am not sure I am skilled enough not to screw it up.
hopefully I will be able to afford a bed and saddle regrind at some point but probably not for a few years yet. So if I can avoid removing material now that is the safest bet
1 March 2021 at 21:55 #531075
Neil Wyatt
Moderator
@neilwyatt
Can't be a bad idea as Myford changed to using the system on later S7s.

Neil
1 March 2021 at 22:01 #531077
duncan webster 1
Participant
@duncanwebster1
This might be a stupid idea, but you can buy Glacier DU bearing as strip, could this be glued to the rear shear?
1 March 2021 at 23:53 #531086
peak4
Participant
@peak4
Posted by duncan webster on 01/03/2021 22:01:23:

This might be a stupid idea, but you can buy Glacier DU bearing as strip, could this be glued to the rear shear?

Never used that, but I did use some Tribo Tape B160 when I refurbished my surface grinder.
I bought enough to do the same job on my Myford S7. It should be just thick enough to give clearance, without causing problems by moving the saddle too far to the rear.

https://www.igus.co.uk/tribo-tape/tribo-tape

Bill

Edited By peak4 on 01/03/2021 23:53:59
2 March 2021 at 07:20 #531100
Alan Charleston
Participant
@alancharleston78882
Hi Bill,

Is the Tribo Tape B160 the same as Turcite which I believe is teflon loaded with bronze powder?

Regards,

Alan
2 March 2021 at 07:42 #531101
Hopper
Participant
@hopper
Posted by JDS on 01/03/2021 19:19:17:

I did think about trying to but I am not sure I am skilled enough not to screw it up.
hopefully I will be able to afford a bed and saddle regrind at some point but probably not for a few years yet. So if I can avoid removing material now that is the safest bet

Use the Barker Method of wide guide conversion described in detail in MEW 287 and you won't have to remove metal and will not need a milling machine, unlike the Radford and Ganderton methods.

It consists of doing more or less what you have started: add a strip of gauge plate along that back edge so it bears on the very rear shear instead of the worn front shear. The article describes using 1/16" or 3/32" gauge plate, but others on here have used a thinner strip of feeler gauge material and loctited it in place.

The Turcite tape sound good too.

I would not use the soft Glacier bearing material for fear swarf would embed in it and make a nice grinding surface.
2 March 2021 at 07:42 #531102
Neil Lickfold
Participant
@neillickfold44316
I added constant oiling to my S7. I just change the viscosity of the oil until it works. Currently using ATF oil with a bit of lucas oil stabilizer. Works really well. With hindsight I should hav eused 6mm fitting instead of 4mm fittings. The 4mm is a bit restrictive with the oil. If i need a higher viscosity, it will need the bigger id tubing.

Edited By Neil Lickfold on 02/03/2021 07:44:09
2 March 2021 at 08:38 #531136
Hopper
Participant
@hopper
Posted by Neil Lickfold on 02/03/2021 07:42:42:

I added constant oiling to my S7. I just change the viscosity of the oil until it works. Currently using ATF oil with a bit of lucas oil stabilizer. Works really well. With hindsight I should hav eused 6mm fitting instead of 4mm fittings. The 4mm is a bit restrictive with the oil. If i need a higher viscosity, it will need the bigger id tubing.

Edited By Neil Lickfold on 02/03/2021 07:44:09

Is that using a pressure feed? What do you use to make the pressure? Is there are commercial system that can be fitted?
2 March 2021 at 13:44 #531211
peak4
Participant
@peak4
Posted by Alan Charleston on 02/03/2021 07:20:29:

Hi Bill,

Is the Tribo Tape B160 the same as Turcite which I believe is teflon loaded with bronze powder?

Regards,

Alan

As far as I'm aware, it's just a very hard, but slightly flexible plastic of uniform thickness.
You can get plain or self adhesive, when I measured my own Myford S7, I reckoned I needed the self adhesive for the extra thickness; it should give me enough thou clearance without machining the saddle casting.
From what I can gather, it's significantly cheaper than stuff such as Turcite.
It's probably even cheaper than a couple of bits of 12" Starrett feeler gauge strip

Bill
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