Mini Lathe Upgrade

[COLIN MARTIN 2Participant @colinmartin2]

Hi All,

Apologies for the subject, but I'm interested in other member's experiences along the same route.

I have a Conquest mini lathe that has served me well over about fifteen years, making and modifying motorcycle parts, but two points are a problem: the 80mm chuck is too small, and the poor headstock rigidity makes parting off a real problem. I am considering changing to a 100mm chuck and replacing the bearings with angular thrust ones, but I'm not sure if the 300w motor is going to be beefy enough.

So, I am considering a new mini lathe, which comes with the 100mm chuck and more powerful motor, but by the time all the extras like 4 jaw chuck, faceplate and steadies are added, works out at about £700. Alternatively, I can buy a Chester DB7VS, which comes with the four jaw chuck, faceplate and two steadies for about the same money. Any opinions please? Should I look for a Myford ML10 instead? Thank you.

[COLIN MARTIN 2Participant @colinmartin2]

[Neil WyattModerator @neilwyatt]

Hi Colin,

I'd be inclined to get a brushless mini lathe with standard size chuck and use a 100mm chuck with a backplate.

You can then use your existing 80mm chuck(s) faceplates and accessories and also have the advantage they can be used over the cross slide.

There are few, if any, disadvantages of using a 100mm chuck with a backplate.

This is how my mini lathe is set up, which is an ancient CL300M upgraded with roller bearings and also fitted with a half-horse 3-phase motor.

After fitting the bearing upgrade I never had any real issues with parting off.

Neil

[COLIN MARTIN 2Participant @colinmartin2]

Hi Neil,

Thanks, I suppose we have all been in the position of being caught in a dilemma. I'm mulling things over in my head!

Colin

[Bob StevensonParticipant @bobstevenson13909]

I used a Conquest mini-lathe for about 10 years but changed two years ago to a Warco WM180 which is a sibling machine to DB7. I liked my mini-lathe and have defended mini-lathe on this forum, however, the WM180 is vastly superior in just about every way and I have been delighted with it's many improvements over mini-lathe.

[LainchyParticipant @lainchy]

Hi Colin,

I have a DB7, and still struggle with parting off occasionally, mainly in steel, but a 3/32" parting blade seems to work the best. Keep it slow and well lubricated. No problems parting anything else off though. A friend has the SC3 which I believe is similar to the conquest??? and his headstock bearings have been upgraded – it works really well, albeit 500w.

If it were me… and machining motorcycle parts which I assume will be good quality steel, I'd go for either the SC4 or Axminster/Warco/Chester variants (If brushless, and if you can stretch that far budget wise) Not sure about the Myford ML10

I'm a beginner, but personally, if mainly machining Steel… I'd want a bit more grunt, hence the SC4 suggestion.

[HollowpointParticipant @hollowpoint]

If it was my money I would be looking to upgrade to a larger machine. The mini lathes are OK but they lack rigidity. They do seem to hold there value though so that might help pay for the upgrade.

I can't comment on the db7 because I've never had one. I have had an ML10 though and it's a lovely machine! The biggest drawback as with the ML7 is the limited spindle bore. Not ideal if you are making motorcycle parts. My current lathe is a Boxford AUD which beats the others mentioned hands down. This would be a perfect choice for you as it has a good bore size and my own will part through most stuff with ease. An AUD would set you back £1000+ though. You might be lucky though and find a CUD or BUD within your budget. That would be my suggestion, the difference between your mini lathe and the Boxford would be noticeable.

[COLIN MARTIN 2Participant @colinmartin2]

Thanks everyone for the suggestions. Everything is a compromise between, space, weight, money and size v what I wish to do. There is a Chester retail outlet near me, so I will go along and have a look at a DB7VS, and then spend some time mulling things over.

[Ron LadenParticipant @ronladen17547]

Colin, unless I am missing something the DB7VS is on the Chester site for £838 not £700 and yes it does come with a 4 jaw and the steadies but I dont see a face plate listed. Also it is only a 12 inch machine which is rather small unless you know you wont need anything longer, Chester claim 700 watts and I could be wrong but I think it is a 600 watt motor fitted. I am not trying to put you off or knock the machine it may be a nice little lathe, probably is, but I just thought I would mention those points in case you have missed them.

Have you considered their 920 lathe that is a 9 inch x 20 inch against the 7 inch x 12 inch of the DB7 and £25 cheaper. You mentioned getting over the problems you have with parting off, a bonus on the 920 is that it has a T slotted cross slide which means you could fit a rear tool post for parting. I have a rear tool post on my Warco 920 and parting is a pleasure to do with no issues.

Just a bit of food for thought for when you go to Chesters to see the DB7 have a look at the 920 as well.

Edited By Ron Laden on 24/11/2019 15:41:42

[COLIN MARTIN 2Participant @colinmartin2]

Yes, thanks Ron,

I do think that the Chester 920 looks very good, but I'm worried about the weight as I'm not as young as I was and space is an issue too.

The DB7 appears to be a good buy with all the extras included, but does work out at £100 dearer than a similarly equipped mini lathe. As everyone on here has probably found, a home lathe can never be too big, but practically it is a compromise. I don't want to struggle to get a heavy piece of kit into place, which definitely rules out the small Harrison and Colchester lathes etc. I'm in no rush, so I will keep !y options open.

[LainchyParticipant @lainchy]

Keep yer eye's open Colin, I managed to pick up my DB7 with all the tooling and a Chester metal stand for £650. …although, I had to drive to South Wales to collect it – around 250 miles round trip for me.

Well work it though, as it was 2 years old and only turned aluminium. I kept watching eBay and Gumtree.

Good luck

[COLIN MARTIN 2Participant @colinmartin2]

UPDATE:

after much thought, I've decided that I can only decide after I know what I am going to need!! It is a bit illogical to buy the same size lathe with just a bigger chuck (even though it is a higher spec) without knowing if it will do the job, therefore I have decided to upgrade my existing lathe and see how I get on with that, then go from there.

I have bought a 100mm chuck (on special offer at the moment from Arc Euro Trade) and a pair of angular thrust bearings, which I hope will stiffen up the spindle, and a new spindle with the flange which takes the 100mm chuck. Big thank you to Arc Euro Trade which sent out the parts for next day delivery and Simon at SPG Tools who supplied the spindle and was most helpful.

I was pleasantly surprised when stripping out the spindle and bearings: after reading a lot of negativity about the quality of workmanship on the mini lathe, I found that the parts were pretty well made, although not awe-inspiring like some engineering, the parts are solid and certainly of acceptable quality. I had expected the Chinese bearings to be shot after about fifteen year's use, but both spun perfectly smoothly and with no trace of play, so in future I will have no hesitation in buying Chinese bearings.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by COLIN MARTIN 2 on 28/11/2019 10:16:33:

UPDATE:

after much thought, I've decided that I can only decide after I know what I am going to need!! It is a bit illogical to buy the same size lathe with just a bigger chuck (even though it is a higher spec) without knowing if it will do the job, therefore I have decided to upgrade my existing lathe and see how I get on with that, then go from there.

I have bought a 100mm chuck (on special offer at the moment from Arc Euro Trade) and a pair of angular thrust bearings, which I hope will stiffen up the spindle, and a new spindle with the flange which takes the 100mm chuck. Big thank you to Arc Euro Trade which sent out the parts for next day delivery and Simon at SPG Tools who supplied the spindle and was most helpful.

I was pleasantly surprised when stripping out the spindle and bearings: after reading a lot of negativity about the quality of workmanship on the mini lathe, I found that the parts were pretty well made, although not awe-inspiring like some engineering, the parts are solid and certainly of acceptable quality. I had expected the Chinese bearings to be shot after about fifteen year's use, but both spun perfectly smoothly and with no trace of play, so in future I will have no hesitation in buying Chinese bearings.

Can we see pictures of spindles side by side and bearings?

It will then be possible to construct the ultimate mini lathe spindle and I will be rich on saturday.

Something along these lines

Edited By Niels Abildgaard on 28/11/2019 12:07:04

[COLIN MARTIN 2Participant @colinmartin2]

The bearings are available from Arc Euro Trade and are a direct replacement for the standard ones. I'll try to post some pictures.

[Ron LadenParticipant @ronladen17547]

Hi Colin,

The changing of the bearings to better quality angular type I would think well worth doing but I cant quite see how they are going to improve rigidity regarding parting off issues. I can only go with the experience I had with my mini -lathe which had the factory fitted bearings which were not top quality but good enough. I never had a problem with the spindle and never thought it lacking in rigidity, the bearings were well adjusted there was no end float, no play and the fact the lathe worked well in normal turning operations sort of proved that.

However I did like you have parting off issues which in the end led to not using a parting tool larger than 1.5mm and I only parted off small parts, I wouldnt attempt anything large. So there was a lack of rigidity but where..? well I think it is a lack of rigidity in the cross slide, top slide and tool post and also a lack of rigidity between them (as a set) and the head. I had no problem with general turning the lathe worked well though I never pushed it too hard and I just based that on accepting that the mini-lathe is a lightweight machine and trying to keep within its limitations.

So what to about the problems with parting off, a few of the guys here on the forum suggested a rear tool post but it did mean making a larger heavier duty cross slide which is no small job. The cross slide on the mini is not really big enough to take a decent rear tool post so I bought a large chunk of cast iron and made a new one with longitudinal T slots and a rear toolpost, picture below.

The end result was a different machine when it came to parting off, I could user larger tools if needed and part larger sizes with no issues at all. Making a new cross slide wouldnt appeal to everyone of course but it was easily the best mod I did to the lathe.

My two penneth anyway and good luck with the bearings, hope they make a difference.

[COLIN MARTIN 2Participant @colinmartin2]

Hi Ron,

I think that you are completely right! I believe that the mini lathe lacks rigidity everywhere because it is quite poorly made and flimsy, but having said that, it is a terrific machine for the money. When comparing it to a bigger, studier lathe, which has so much rigidity in the head, bed and cross-slide, the mini lathe just has too much give in the components, so that the work tries to bend away from the parting tool.

I'm only changing the bearings because I have the spindle out, so it was worth trying the angular contact bearings. It was a mixed decision, because I have a spare pair of original bearings by KYO, which I could have used, but…..

Congratulations on your new cross-slide, maybe a new project for me?

Colin

[Ron LadenParticipant @ronladen17547]

Hi Colin,

I have moved up to a bit bigger lathe now but dont get me wrong I am not knocking the mini-lathe, never would as you say a great machine for the money. Mine taught me a lot and I did some good work on it, I did consider changing the spindle bearings on mine when I had the head stripped to change to metal gears but I put the standard ones back.

The heavier cross slide is a bit of a job but well worth doing should you ever consider it.

Ron

[SillyOldDufferModerator @sillyoldduffer]

Posted by COLIN MARTIN 2 on 29/11/2019 10:04:00:

…I believe that the mini lathe lacks rigidity everywhere because it is quite poorly made and flimsy …

When comparing it to a bigger, studier lathe, which has so much rigidity in the head, bed and cross-slide, the mini lathe just has too much give in the components, so that the work tries to bend away from the parting tool.

…

Much truth in that, but it has to be said that many lathes struggle with parting off, and small ones are particularly troublesome. It's not that mini-lathes are exceptionally flimsy as such, rather that parting off is a severe test. Say a 2mm parting blade is used. The cutting edge is much larger than a point tool and bigger than average forces results. The parting tool operates in a slot liable to jam due to swarf or heat, and, if it dips for any reason, it's liable to dig in.

The forces applied by a 2mm cutter to a small lathe are the same as those applied to a bigger lathe : it's not surprising that big machines cope better.

But even big machines may not cope well with parting off. Anything allowing the cutting edge to dip will cause trouble. Worn beds allowing the saddle to rock, loose gibs (due to wear or maladjustment), not locking unused moving parts, excessive tool reach, jerky operator, bendy tool-post etc etc. Old Model Engineer magazines often discuss parting-off problems: no-one had a mini-lathe back then!

My WM280 can part off from the 4-way tool-post most of the time, but the cure-all is a hefty rear-mounted tool-post. The solid construction and position on the saddle of a rear tool-post enables any lathe to absorb significantly more force without dipping and vibration. Even so, it's still important to maintain a steady feed, to lubricate, and to clear swarf. I suspect a mini-lathe fitted with a rear tool-post would part off reasonably well, but fitting one means modifying the saddle. As space and the saddle design on a mini-lathe limits what can be done, not many are fitted with rear-tool posts!

I avoided parting off on my mini-lathe, preferring to remove the job to saw it, and then replacing to face-off. Wasted a bit of time, but a mostly suitable alternative. The lathe would part-off Brass OK, but Steel and Aluminium were more trouble than it was worth.

Dave

[COLIN MARTIN 2Participant @colinmartin2]

Yes, good points. I tend to avoid parting off if I can, just using it for thin wall tubes, but it would be nice to have more options. I watched a great video on YouTube recently that went into great depths on the subject and was really informative. The poster was obviously an experienced toolmaker and he detailed how much he struggled to part-off successfully.

[HOWARDTParticipant @howardt]

I have a Sieg SC3, bought early 2016. Parting off with the machine as supplied is nye on impossible. A couple of years ago I replaced the bed slide keep strips with taper gibs, this helps but all the slides need clamping down. I have taken off the compound slide and replaced it with a riser for the tool post recently as I use the compound so little. When I fitted the gibs I was parting off 50mm steel as i didn't have a band saw at the time, From what I can see the main problem is with the cross slide width and fitting, as you part off the slide tries to rotate 90 degrees to the spindle causing the tip to move sideways and down to dig in. When I have time I shall make a better fitting gib and see if this helps.

Just my two penth.

Howard

[COLIN MARTIN 2Participant @colinmartin2]

I'm wondering if a saddle clamp would help?

[LainchyParticipant @lainchy]

Asking as a noob, would it be worth moving the compound back so the parting tool is on the centreline on the cross slide, and that the cross slide gibs are very well adjusted? I assume so.

Regards

Ian

[Ron LadenParticipant @ronladen17547]

Ian, that probably would help a bit but I think the bottom line is that the cross/compound slides and tool post are just not rigid enough. They are fine for general turning though so dont let it put anyone off the mini they are good machines but parting really does test the mini lathe at least it did mine.

Having said that I have read on a number of occasions people saying that their mini-lathe is fine with parting and they regularly part 50 – 60mm steel bar with no issues..? That is not my experience with the mini and it was only after I made the heavier cross slide and rear post that I could tackle that size of job.

[COLIN MARTIN 2Participant @colinmartin2]

Right, as promised, here is the run-down on changing the spindle to a later type with the mounting for a 100mm chuck.

It is pretty simple; I removed the chuck, took off the cover at the gear end and unscrewed two allen screws that hold on a cast aluminium plate, giving access to the two ring nuts on the end of the shaft. By holding the chuck flange these can be uscrewed using a 'c' spanner and the drive gear and plastic spacer removed. A simple puller has to be devised, using a flat piece of bar with a centre hold drilled; with this held off the end of the chuck flange by two lengths of tubing against the headstock, a long bolt can be passed through the spindle and the nut on the end tightened, drawing out the spindle and end bearing. The remaining bearing is tapped out of its housing.

The top picture shows the new angular thrust bearing on the left, old ball race on right. The lower picture shows old spindle at the top, new at the bottom.

Fitting was simple – press new bearing onto shaft and then feed shaft through the plastic drive gears – although this presents the problem of how to get the bearing into its housing – I managed to tap it in by inserting a small rod through the chuck mounting holes and working around the bearing until it was snug. The bearings are a really tight fit upon the shaft, but because the angular thrust bearings need to be adjusted to remove any end-float, ideally the bearing at the other end should be a tight sliding fit upon the shaft, but after much use of emery cloth, I still was not able to get it as loose as I would have liked. I had to resort to tapping the bearing into the housing, while gently tapping the inner race onto the shaft. finally I tightened the end nuts to remove any end-float and all was well. one small problem is that the tiny parallel key in the end of the shaft is shorter on the new one, so I had to make one to fit. If anyone is ordering the new shaft, be sure to include a new small key.

The new chuck is supplied with mounting bolts that will not fit behind the flange, so I made up some studs and screwed these into the back of the chuck mounting holes. I stripped and cleaned the chuck before use to remove swarf, which other internet videos have shown to be necessary. The chuck is pretty impressive for something so cheap and I only have runout on a length of ground rod in the jaws of half a thou, so all in all I am very pleased.

[COLIN MARTIN 2Participant @colinmartin2]

I've been busy doing a few more jobs on the lathe to try and improve it. A few days ago some play developed on the cross-slide area, which I traced to the saddle; on closer inspection one of the saddle shear plates had fractured where the grub screws are fitted. Those who have fiddled with this abomination will know, and those who have yet to do so will find out, what a stupid bit of design this is.

I found that the rear plate was very close to being right without the grub screws, so used pieces of 15thou shim to take out the play, but the front shear plate needed a lot of shimming, which was going to be very difficult to get right, so I found that a small spring washer sandwiched between the plate and the saddle was a perfect fit, so replaced the three Allen screws with small studs, fitted spring washers over each stud, replaced the plate, and fastened it with nylock nuts. Then using feeler gauges, was able to tighten the nuts evenly until the saddle was a good fit over the bed. While the lathe was apart, I also made a cover to go over the handwheel gear housing.

Lastly, I have made a swarf tray that fixes to the saddle, to keep chips away from the leadscrew and lathe bed. You are never bored when you have a mini lathe.

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