Mini-lathe saddle casting error.

[modeng2000Participant @modeng2000]

I recently bought a fairly cheap mini-lathe and all seemed as expected, that is it needed a going over to set up the various adjustments.The first time I face turned a bar the result wasn't as expected. The surface is convex and the error from flat is of the order of 0.5mm in 100mm. I believe it is normal for there to be a slight deviation from flat but this is excessive.

Without any machining facilities to correct the saddle is there anything i can do to reduce the error? The top slide cannot be positioned to do the final surfacing so that I can finish this job. I only have hand tools available so am I right in thinking the best solution would be to replace the saddle?

John

[modeng2000Participant @modeng2000]

[JasonBModerator @jasonb]

A tiny amount of Concave is said to be acceptable but not convex.

First thing would be to contact the supplier assuming you bought it new.

[RobCoxParticipant @robcox]

Firstly, any deviation should result in a concave surface, not convex. 0.5mm in 100 sounds terrible to me.

It's not necessarily the carriage or cross slide that's at fault here. It might be that the headstock isn't parallel to the ways.

Correcting this isn't as simple as clamping it on a milling machine or grinder and having at it. Firstly an exhaustive examination of all the parts mentioned above would be in order to determine which part(s) are at fault. Next, removing metal from the saddle v ways would alter its height, resulting in less engagement on the carriage rack. If it's the headstock at fault the tailstock would need attention too.

You might have to decide if it's worth trying to fix as without the required expertise you might make it worse and write it off. If it were bought new I'd be angling for a refund or replacement.

Rob

[Pete RimmerParticipant @peterimmer30576]

As Rob says first check that it turns parallel by turning a part held only in the chuck. If that is acceptable, then it's time to look at the saddle's cross-slide way closest to the chuck.

Edited By Pete Rimmer on 30/12/2021 17:13:21

[john fletcher 1Participant @johnfletcher1]

A friend very recently bought a small lathe and had a similar problem . Apparently under the saddle are two screws which were very loose, fortunately another friend turn up and he had exactly the same problem when he bought his small lathe. I'm told they need going over and tweeking before use, otherwise good for the price. John

[modeng2000Participant @modeng2000]

Thanks for the wise words. I have checked that the lathe turns parallel so that is why I believe it must be the saddle. Using a square against the crosslide side shows an out of square similar to the measured error. The crosslide and saddle sides check as true rectangles.

John, I'll have a look for these screws but I haven't noticed them before. If they are not present then I guess it's back to the supplier.

John

[modeng2000Participant @modeng2000]

A bit more measuring and I find that the saddle topslide register is not parallel with the side of the saddle, the error being such as to create the convex turning. The saddle side is at 90 degrees to the lathe bed. Deduction is that the saddle has been machined incorrectly.

John

[MikeKParticipant @mikek40713]

As mentioned, check the headstock, which is something you can easily adjust with shims. The procedure I used, I think, was from the Yahoo mini-lathe user group…which of course is DOA, but I believe all of the files and such have been moved to the mini-lathe group on the groups.io site.

[modeng2000Participant @modeng2000]

Thanks Mikek, I believe the headstock is true to the lathe bed.

John

[modeng2000Participant @modeng2000]

I have sent the requested photographic information. We wait to see what happens next.

John

[not done it yetParticipant @notdoneityet]

Posted by modeng2000 on 31/12/2021 15:48:13:

I have sent the requested photographic information. We wait to see what happens next.

John

That smacks of a chinese supplier. Typical of them to request photograhic evidence – even of missing parts.🙂

[modeng2000Participant @modeng2000]

'That smacks of a chinese supplier'

Yes, but I suppose it is not unreasonable. There are those around who like to try their luck.

Anyway I'll go along with them for now.

John

[modeng2000Participant @modeng2000]

The next chapter:- they said they were not able to see the error using the photographs I sent, or so they said!

Now they are asking for a video. I'll go along with this and see what they ask for next.

John

[Chris TriceParticipant @christrice43267]

Put a straight edge across the surface and slip a feeler gauge between the part and the straight edge. That should tell the story.

[John HaineParticipant @johnhaine32865]

Some further information would be useful. What type of lathe is it, the generic mini-lathe? What badge does it bear? Did you buy it new, and who supplied it?

A lathe with that degree of error is not fit for purpose. If you bought it new in the UK then the supplier should replace it or refund your money. It is likely that the supplier will be concerned about making further sales to amateurs, so please name and shame them on here. Finally, if you can post the photos you took then maybe we can recommend a better process for taking meaningful pictures to prove the problem. Frankly I can't see how a video helps except in kicking the can along the road a bit further in the hope that you will give up.

And if the lathe was bought new the DO NOT make any attempt to fix the problem which would be an excuse for wriggling out from any warranty.

[OldironParticipant @oldiron]

I agree 100% with John Haine above. If UK supplier give them a call as they should be your first point of contact. And DO NOT try any repairs until you have exhausted all avenues of warranty and returns.

regards

[modeng2000Participant @modeng2000]

Thanks all for the continuing advice.

At this point I'm not going to give details of the make or supplier of this lathe. As I wrote at the begining, it is a low price mini lathe and I expected to have to make adjustments. However there is no adjustment for this fault.

It is fair to give them the chance to provide a solution. If that is not forthcoming then perhaps is the time to identify.

John

[modeng2000Participant @modeng2000]

Have received a reply to my videos expressing regret that the machine is not up to standard.

Have been offered a replacement machine and no need to return the old one. I am left wondering what the word machine includes, perhaps just the rep[lacement crosslide machined casting.

Time will tell.

John

[modeng2000Participant @modeng2000]

I am very pleased to have a resolution to the faulty saddle problem. The company has recompensed me and now that I have an accurate machine I can perhaps get on with the job that showed up the error.

John

[Roger KnillParticipant @rogerknill77723]

Glad you got it resolved.

would be interested in finding out what lathe it was and who the vendor was. You hear a lot of stories of poor quality and poor customer service, it’s good to hear of a seller willing to put right mistakes that do happen. Did they replace the whole lathe or just the saddle?

thnaks

Roger

[modeng2000Participant @modeng2000]

Hi Roger, I couldn't have had better service from Vevor, they were really helpful but as expected required proof of the faulty part. The resolution was to send me a replacement lathe, I suspect they do not hold spare parts themselves. I looked into obtaining a new crosslide and this cost around £45 so the obvious thing to do was to buy one to effect the cure.

Feeling guilty accepting a whole new machine I suggested I ought to return the secomd lathe but was informed I could keep it and use it as I wished. The restocking cost made the return uneconomic for Vevor. I should add the lathe is the cheapest in their range at £380 or thereabouts.

I have made various improvements to the original and now it is quite acceptable.

John

[Ketan SwaliParticipant @ketanswali79440]

Hi John – modeng2000 and all,

This is an observation, rather than a criticism. I am not looking to offend anyone.

This morning, we had a call from a customer who had the same machine from the same supplier, with a blown control board. He too has a replacement machine coming from Vevor. He also purchased tooling from them which he believes to be of poor quality.

As a result of his experience, his general opinion of 'mini-lathes and tooling' from China was that they are all of poor quality. We helped him understand the tooling he had purchased and we helped him understand that the mini-lathe he purchased was totally different to what is sold by reputable U.K. sellers.

Buying machines and related products from eBay, Amazon or Vevor, from unregulated foreign entities come with their own set of issues – good, bad and ugly.

I can understand that the purchase is made because the machine and tooling was cheap. However, the only buyers who should take such risks are those who know what to expect for the price, and be happy to be able to fix it if things go wrong.

Sadly, a high percentage of buyers who buy such cheap machines have very low engineering knowledge or experience. If it is right or wrong to go down this road, is really up to the buyer.

However, it is concerning if people get put off the hobby based on this experience, and it is wrong for all reputable sellers to be tarred with the brush of 'all Chinese mini-lathes and related products' are rubbish.

In the case of the person who called us, he purchased some tooling from us. In his case, according to him, he will get the replacement machine, and then off-load a working machine on eBay… probably for someone else to experience. Then he will purchase a new mini-lathe from us.

For ARC, there is a silver lining.. We get calls as per above example, every few days. Many turn into new customers, to whom we sell mechanical spares, and new tooling, or new machines. They then turn into regular customers. Unfortunately, in all cases we cannot help them with the electronics…control board replacement, as they are totally different to those fitted in SIEG made mini-lathes.

So John and all.. If you really know what you are doing with a cheap purchase, ….please don't feel guilty for accepting a new replacement machine from Vevor or any other unregulated foreign operator off eBay, Amazon or elsewhere. The more such operators are hit financially for their incompetence, the more they will realise that it is not an easy revenue stream.

However, it is difficult to say how many NEW people have been put off the hobby resulting from their experience.

Ketan at ARC

[modeng2000Participant @modeng2000]

Hello Ketan, I fully understand your position in this question of sourcing mini-lathes. In my case I was prepared to have to make improvements and so was not put off by all the necessary adjustments and modifications needed to make the lathe into a usable machine. However I did not expect to have such a basic fault, thankfully now sorted. My original posting was for advice and I certainly received good advice and I think I detected some anti feeling towards this type of mini-lathe.

As I said, I went into this purchase with my eyes open and so as you rightly say, you get what you pay for. I do wonder if the person who bought my replacement lathe is now one of your customers.

I have purchased form you in the past and no doubt will do do again.

John

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