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Warco Mini Lathe

Lose saddle

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Peter Russell 421/06/2019 22:13:55
59 forum posts
1 photos

Ive had my Warco mini lathe for a few years and have never been able to part off ithout the carriage jumping, the tool jamming and either the parting tool breaking or the belt stripping.

I changed to metal gears quite quickly and brass gibs in the early days.

Ive now stripped the carriage assembly to fit DRO but on re assembly have I think discovered the problem Ive had from day one.

The saddle asembly when clamped down corectly is capable of being rotated a few degrees each way which there is as far a I can see no adjustment for ie no gibbs.

It gives the appearance that the bed V is too narrow or the grove in the saddle is too wide.

The unit is out of waranty and it is pointless considering further re assembly as it will not result in a viable machine.

Any one else had same problem and how did you resolve it.

My current idea is to scrap it and buy new. But not Warco

Pete

David George 121/06/2019 22:32:27
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841 forum posts
292 photos

Can you put some pictures for us to see problem.

David

Bob Stevenson21/06/2019 23:02:29
285 forum posts
6 photos

Hopefully someone deserving will get a nice little bargain!.......this problem is solved fairly easily with a little knowhow two pieces of brass plate......

Martin Hamilton 121/06/2019 23:25:36
107 forum posts

Care to share how that is done Bob. Thanks.

Bob Stevenson22/06/2019 07:17:02
285 forum posts
6 photos

Nope....He's obviously made a calculated asessment and "the internets your friend" if his mind changes.

Simon Collier22/06/2019 07:23:20
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297 forum posts
52 photos

A friend's SC 3 had this problem. It made the lathe unusable. The fix was very easy once I diagnosed what was going on. I simply put a sheet of thin brass shim between the saddle and the bed at the front ways. It was not fixed in any way, but nevertheless it moved with the saddle. I chucked a length of 1" bms about 8" long with tailstock support and took a cut with the finest lead screw feed and sharp HSS tool. Beautiful finish. Lathe transformed into a capable machine.

It is appalling that machines like this are sold, especially to beginners who are least able to understand the faults and fix them where possible.

Michael Gilligan22/06/2019 08:38:01
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13573 forum posts
586 photos
Posted by Bob Stevenson on 22/06/2019 07:17:02:

Nope....He's obviously made a calculated asessment and "the internets your friend" if his mind changes.

.

That's strange, Bob

I read the opening post as being from someone seeking advice, because he doesn't know how to make the lathe useable, and is currently thinking he might need to scrap it.

MichaelG.

.

[quote]

Any one else had same problem and how did you resolve it.

My current idea is to scrap it and buy new. But not Warco

[/quote]

Brian G22/06/2019 08:50:56
513 forum posts
11 photos
Posted by Peter Russell 4 on 21/06/2019 22:13:55:

...The saddle asembly when clamped down corectly is capable of being rotated a few degrees each way which there is as far a I can see no adjustment for ie no gibbs.

It gives the appearance that the bed V is too narrow or the grove in the saddle is too wide....

When it isn't clamped down, can you move the saddle in and out as well as rotate it? If not, it is possible that the saddle is resting correctly on the V in the centre and not the ends, rather than the V being too narrow.

It took quite a bit of work with fine abrasive (I have never learnt scraping) to sort this on my son's machine. I don't believe the saddle can have worn that much as the machine had not been heavily used, and assume the casting must have warped after manufacture so that the middle of the v-slot was lower than the ends.

With this work and the addition of a saddle lock (simply done on the Warco by drilling a hole in the saddle between the ways to the right of the cross slide) parting off was much improved. Further improvement came by adding two more gib screw holes to the cross and compound slides, allowing the centre screw on the compound to be used as a lock.

Brian

SillyOldDuffer22/06/2019 09:51:25
4536 forum posts
971 photos

Well, parting-off is and always has been notoriously difficult! It's a recurring topic in Model Engineer magazine for over a hundred years. The main answer seems to be rigidity and smooth feed-rate, which means small manual lathes are automatically at a disadvantage. After a fair amount of practice, I was able to part off on my Warco mini-lathe with plastic gears and unmodified gibs and I never damaged a belt. But not an operation I enjoyed, in fact I avoided parting off on my mini-lathe whenever possible due to the risk of jams and broken tools.

Whilst shimming the rear of the saddle will stiffen it up usefully, I'm not convinced the saddle is the main problem. My chief suspect is the front tool-post. On many lathes they are clamped to the saddle with a single bolt, but far, far worse, is that they tower high above the bed, and are relatively lightly made. The whole assembly is bendy! Then the tool-post is fitted with a long sticky-out parting tool to take an unusually heavy cut in a swarf filled slot. The leverage applied when the tool digs in is substantial. Nasty. A mini-lathe needs all the help it can get, lubrication, swarf clearance, sharp tool carefully set, and above all a steady hand.

Two obvious cures:

  • Buy a bigger lathe: heavy lathes with hefty parts are much better placed to deal with parting off forces. The bigger the better!
  • Fit a rear tool-post of Gibraltar type. (Not easy on most small lathes due to lack of metal.)

I'm a little suspicious of rear shimming as a solution. The saddle's accuracy is determined by running along the precision 'V'. There's a risk shimming might mis-steer the saddle relative to the ordinary rear of the bed instead. But people do shim successfully; perhaps the trick is shims loose enough to flex slightly under normal operation, but tight enough to restrict the saddle whilst parting?

Don't be too quick to blame Warco in particular. As the design is pretty much generic, make sure the same issue doesn't apply to candidate replacements. Really annoying to buy a new lathe and discover it has exactly the same problem.

Hacksaw marks on second-hand bed lathes are rather common. It's because previous owners chose to saw work off instead of parting off. Good idea to protect the bed with a bit of wood!.

Dave

 

Edited By SillyOldDuffer on 22/06/2019 09:52:06

Martin of Wick22/06/2019 10:33:30
81 forum posts
4 photos

I had a similar saddle rock problem with that type of lathe, seems to be quite a common problem. Check there isn't a burr or warp on the saddle base . In my case there seemed to be a slight bulge. Perform the tests and checks above to be confidant you have properly diagnosed the problem.

Check out this link to see a method I used to ensure a good fit of the saddle to bed - seems complicates but is actually very easy and quick- go carefully as it is easy to over do it! **LINK**

I find it hard to believe the vee in the saddle is really wider than the prism it sits on, but it is possible through bad manufacture. If this is truly the case and the misfit is gross, shimming may be an option.

Alternatively, you will find you can obtain a complete new saddle from one of the partners (in no particular order ARC Amadeal others etc.) on this site will not break the bank (typically <£30.0).

Barrie Lever22/06/2019 11:29:50
323 forum posts
1 photos
Posted by Peter Russell 4 on 21/06/2019 22:13:55:

Ive had my Warco mini lathe for a few years and have never been able to part off ithout the carriage jumping, the tool jamming and either the parting tool breaking or the belt stripping.

I changed to metal gears quite quickly and brass gibs in the early days.

Ive now stripped the carriage assembly to fit DRO but on re assembly have I think discovered the problem Ive had from day one.

The saddle asembly when clamped down corectly is capable of being rotated a few degrees each way which there is as far a I can see no adjustment for ie no gibbs.

It gives the appearance that the bed V is too narrow or the grove in the saddle is too wide.

The unit is out of waranty and it is pointless considering further re assembly as it will not result in a viable machine.

Any one else had same problem and how did you resolve it.

My current idea is to scrap it and buy new. But not Warco

Pete

Pete

I agree with your current idea.

B.

Hollowpoint22/06/2019 12:23:11
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198 forum posts
27 photos

I've seen this problem come up on several occasions. Most of the DIY fixes I've seen involve using shims or making permanent modifications to the saddle/plates.

It got me thinking, essentially we are trying to get the saddle to clamp to the lathe bed as tightly as possible but still allow ease of movement? correct?

Why not make a replacement saddle plate with a row of bearings in contact with the underside of the lathe bed? You could then tighten the saddle down quite considerably and still maintain perfectly smooth operation. I've never seen this been done its just an idea of mine. It seems like an obvious solution so what am I missing?

Michael Gilligan22/06/2019 12:32:51
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13573 forum posts
586 photos
Posted by Hollowpoint on 22/06/2019 12:23:11:

I've seen this problem come up on several occasions. Most of the DIY fixes I've seen involve using shims or making permanent modifications to the saddle/plates.

It got me thinking, essentially we are trying to get the saddle to clamp to the lathe bed as tightly as possible but still allow ease of movement? correct?

Why not make a replacement saddle plate with a row of bearings in contact with the underside of the lathe bed? You could then tighten the saddle down quite considerably and still maintain perfectly smooth operation. I've never seen this been done its just an idea of mine. It seems like an obvious solution so what am I missing?

.

This is a wild guess, because I have never got that close to a minilathe, but ... it may be that top and bottom of bed are not sufficiently parallel for your bearings to work effectively.

MichaelG.

Neil Wyatt22/06/2019 12:38:20
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Moderator
16277 forum posts
679 photos
74 articles

Unless you fully dis-assemble a mini lathe it's easy not to notice that between the three saddle plate cap screws are two grub-screw adjusters.

If you tighten the screws without backing off the adjusters it is very hard to get rid of play AND if you do it's because you have distorted the plates and they will only make poor contact*.

So loosen off the grub screws, adjust the cap screws until just too tight, then tighten the grub screws which should lock the plates in the right spot. It may need a little effort to get just right

A perfectly good system, but not understood by most mini-lathe owners as it is rarely documented.

Neil

*I know because I did this, the high points wore and I needed to replace the plates, which now are great being properly adjusted.

Neil Wyatt22/06/2019 12:45:57
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Moderator
16277 forum posts
679 photos
74 articles

Here's an extract for an article I wrote for Model Engineer about 16 years ago(!)

The saddle travels along the bed of the lathe, held rigid by two strips bearing on surfaces under the edges of the bed. It is easy not to notice these, and even easier to forget to lubricate them! Any slack in the fit will result in side-to side movement when engaging auto-feed or changing direction with the hand feed. To set this properly you need to unbolt the ‘apron’ from the front of the slide and move it to the tailstock end of the bed. This is awkward to do, as the clasp nuts will not allow the apron to be completely removed, without withdrawing the entire leadscrew. This will reveal the bolts and grub screw. A similar set-up is at the back of the lathe. The grub screws set the fit, but the larger bolts actually hold the strips in position. Because there is some spring in the strips, there is some give and take between the two adjustments. Take care, if the grub screws are in too far, you will need to overtighten the bolts, bowing the strip and reducing its effectiveness.

I adjusted the strips by loosening the bolts, and then backing off the grubscrews. I then experimented with tightening the bolts and grubscrews until I could move the saddle back and forth by hand, but with no movement if I tried to wobble or twist the saddle on the bed. A fingertip on the junction of slide and bed is very sensitive. Another guide is to look for movement in the bead of oil along the junction of the sliding surfaces. It took some time, but at the finish I felt the strips were tightened evenly along their lengths, with no play yet the slide was moving more freely than before I started.


[1] The saddle with the apron removed.

Parting isn't a problem for mini lathes, it's setting them up that is the bit that requires patience, made difficult by poor documentation.

parted.jpg

Simon Collier22/06/2019 12:55:46
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297 forum posts
52 photos

Martin, the V in the saddle really was wider ( and horribly machined) than the prism it sat on in the SC3 I mentioned above. The saddle could be grabbed and rotated. The shim, and adjusting the saddle plate at the back, were an easy solution. Why wouldn't you try this very easy method first?

Martin Hamilton 122/06/2019 14:23:57
107 forum posts

This movement of the saddle is not just a problem on the Chinese mini lathes, at least on the mini lathes there are adjustment grub screws on the front & rear shear plates as Neil talks about in his article. The larger Chinese lathes ( Warco WM180, WM240,WM250 etc ) as far as i understand have no adjustments at all on both shear plates of the saddles. I know some of these lathes you can lift the saddle up & down which also allows the saddle to twist front to back where the v in the saddle can ride up the v on the bed. I believe that on the Sieg SC4 lathe which is comparable in size to some of the slightly larger lathes over the mini lathes do also come with adjusting screws in the shear plates so allowing up & down movement of the saddle to be reduced.

Martin Hamilton 122/06/2019 15:43:32
107 forum posts

This very saddle movement being talked about is one of the reasons (+ a number of other problems) why i got shot of my new Wabeco D4000 lathe after only a very short period. Once you have had a machine for a while you start to discover these problems over time of use, the carriage could be lifted up & down quite a bit which allowed back & forth movement as well as rocking & twisting of the saddle. Resulting in a terrible finish even on aluminium, carbide insert tools were a no no as the results were even worse & it was only usable with very sharp hss tools. There was no adjustment what so ever to prevent the saddle movement which was excessive + it didn't help with the back & forth movement of the cross slide, which had no adjustment on the cross slide nut to take out back lash between the nut & lead screw. When the lathe was new it had about .006" movement on the cross slide, after about 6 months of light use it developed to .012". Factor in the movement in just these 2 areas alone made the lathe undesirable to use & it had to go, i hated the Wabeco.

ChrisB22/06/2019 17:01:48
371 forum posts
152 photos

Is the strip Neil mentioned the one marked in red?

On my WM280, I found the saddle would move slightly up and down when I applied force at the rear of the saddle. When I tightened the four allen bolts, the play on the saddle was gone, but the carriage was jammed, so I used shims to get minimum play with minimum drag on the carriage. Did not find any adjuster screws on the strip, shims worked fine.

carriage.jpg

Martin Hamilton 122/06/2019 18:32:55
107 forum posts

One of the problems you can get Chinese lathes is that the flat ways both front & rear ways is they are not always machined an even thickness along the bed length. You can only adjust the saddle whether it has adjusting screws or shims added to suit the thickest part of the ways, other wise the saddle locks up. I have seen this mentioned a few times by those that have adjusted the saddle either with the grub screws that are on mini lathes or larger lathes that have been modded to reduce movement. They say get the suitable fit on the saddle towards the head stock end of the bed only to find the saddle locks up going further towards the tail stock end of the bed or vice versa due to the variation on the thickness along the bed of the ways. I know some have got around this problem by tightening the shear plates front & back until they find resistance but still able to slide the saddle & have then lapped the shear plates/ways thickness with grinding paste to get a more consistant thickness along the bed front & rear. This can become time consuming doing this & providing you only need to remove a small amount of material along the bed.

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