Thread: New lathe questions (yep)

Geez I'd like a dollar for all the times this question has been asked, still that's what the forum is for. I see the anti Chinese brigade and bottomless pocket brigade have chipped in their usual. For what it's worth I've had 4 or 5 Chinese lathes, never come across sand in the castings and apart from the AL-250 never had a problem. Two of my lathes had auto cross feed, my current lathe doesn't, nice to havebutI don't miss it overly. No doubt the QCG issue will come up, again,, not something I miss overly. As said before, your first lathe will be a teacher you will discover what you require in a lathe. I personally wouldn't get a lathe with all the bells and whistles, the aim is to learn how to use a lathe, get something you can learn on, not something that's going to do it all for you. There's a good market for second hand lathes and they hold their value well.

Originally Posted by PDW

You can make almost anything for anything given enough time & money. The question then reduces to, does it make sense?

For thread cutting I'd want geared speed reduction and no more than 60 rpm.

I wouldn't own a lathe with less than a 25mm spindle bore and 40mm is a lot more useful.

I wouldn't own a lathe that didn't have powered cross slide.

If you buy a lathe shaped object then spend years trying to make it into a competent machine, this becomes your hobby, not the stuff you wanted to actually make using the lathe. Same applies to a complete rebuild of an older machine of course, just your chances of ending up with a better machine improve.

I agree with Michael - if you want longish lengths of Acme thread, buy them. There is no way you can do it as well or as accurately yourself.

PDW

Thanks PDW how long CAN you make an ACME thread then, out of interest? And where do you think the sweet price point is for a lathe at H&F since they're having a sale? I could stretch painfully to 3-4k, but would prefer 2k.


I have read a lot of advice over the net including threads here. I read your advice in a thread PDW that advised to 'buy the Herless' and that thread turned out well. This advice from an American forum seems sensible:
"My advice, then, is to buy
1. a larger used lathe with major assistance from a trusted knowledgeable friend, or
2. the largest new Chicom lathe you can afford, reserving money for tooling, or
3. the smallest new Chicom lathe that seems like it will work, understanding that you may be replacing it - and the tooling - in a year or two."
I don't have any knowledgeable friends, full stop, so scratch out option 1. I've seen the youtube vid on evaluating old lathes and parts sort of confuse me.
Largest lathe that's any good seems to be the AL-336 for $3575 currently at Hafco. This is really stretching my budget (loan time) but I bought a mill with a heap of tooling for $3000 and love it. I hope to keep it a while.
Smallest lathe there that's any good seems to be the $1750 Optimum, or even the $1089 Optimum for hobby use and to teach myself stuff on.
If I was in Adelaide Paramount Browns has a better looking lathe for $2000, but I can't see a similar one in Brisbane. Adding in freight up here sort of kills that deal.

There's no actual limit to the length of thread of any (reasonable) pitch you can cut in a lathe provided the bar fits through the headstock.

Generally though it's the length between centres minus say 50mm or so. I recently did over 400mm of square thread on a 500mm between centres lathe but had to take the tailstock off & use a fixed steady to support the outboard end.

The issues are more that the pitch accuracy is likely to be less than the commercially produced threads and the thread finish is also likely to be worse. Not to mention the time & aggravation doing it. I once made a new lead screw using a big Yamazaki lathe - some 750mm of LH Acme profile thread, 8 TPI. I'd never do it again if I could buy the stuff.

When I was seriously working for a living one of my regular mantras was 'what are we trying to achieve here?'. If you want tooling to build some other device, the tooling - lathe, mill, screws etc - are inputs to the process, not the desired end result. It's easy to lose sight of this. There are more examples in my life than I care to dwell on.

WRT the H&F lathes, I'm currently about 30 minutes away from their Parramatta showroom and it's time I made a visit. But you need to settle in your own mind the work envelope of the lathe you need to get the work you want done. Don't think of makes, country of origin or anything else - just what you want the machine to cut. Aim at 90% of that - really big stuff is better farmed out. Possibly really small stuff as well, or a mini-lathe for the less than 6mm stuff needing really high spindle speeds.

PDW

Everyone has their own opinion and I can offer mine too, but my ideas could be miles out from what you are looking for. That’s the problem, how do you know what you will end up wanting? There are many experts here, but not me, so maybe my experience is useful since I was in exactly the same boat as you, perhaps even more naive. I have an al336 which I have been very happy with. It was my first lathe, having never even seen a lathe before, never mind used one. I didn’t want to buy a small one just to end up getting a new one later so went for the bigger one first off. It was easier to convince herself i needed to get a better one now, as I was warned I better not expect to keep swapping and spending more. Put even more pressure to get it right Probably by luck, it has worked out for me, I have never felt the need to get a bigger lathe and its done everything I need (except a 0.25mm thread). I’ve often been glad I didn’t get a smaller one though. Mine came with a pint of sand in the apron gearbox, but the headstock was reasonable. I stripped and cleaned mine before using it – a good way to learn about your lathe. There was little bits of grit everywhere so a worthwhile job. I think the cross slide is a bit out of spec as far as how perpendicular to the axis of rotation goes, but at least it cuts concave on a face and I wasn’t in a position to even know for the first few years.
It’s not super rigid but I’ve managed to cut a 40 x 6mm internal trapezoidal thread for a car hoist nut (100mm long) but it was in brass only and was really the limit for rigidity in this lathe. I recently cut new nuts for my mill which were 33 x 5mm at 80mm long. I have a picture of that handy so you can see the result. Again, its not super rigid so the results aren’t perfect but it’s Ok for an amateur. I find you have to be careful not to get caught up in chasing perfection for the sake of it.
I have been cleaning up an old mill and the leadscrews were worn in the middle by 0.1mm off the sides of the thread compared to my lathe thread. What I mean is the peaks of the thread in the middle were visibly thinner than at the ends. I used a very sharp carbide cutter to run along the leadscrews to introduce an even wear along the thread, taking nothing off the middle threads. If I didn’t do this, I wouldn’t be able to remove backlash in the middle, and still be able to wind it to the end. The job has proved really successful and I can eliminate backlash along the length now. I’m actually really pleased with how that has turned out, it feels so smooth and precise. I know I have made the mill thread as accurate or inaccurate as my lathe but I have a DRO anyway. I should point out I couldn’t have cut an acme thread on such a long rod though, all I was doing was cleaning up the edge of the thread and not pushing inwards at all. I am not sure I could cut the thread in steel, although I did a successful trial on 6060 aluminium before I committed to Brass which is expensive. I cut an external thread on 6060 so I could offer it up to the brass nut as I was cutting it, because the hoist thread is 2.5m long. Then I saw some expert on here say to take the chuck off and offer it up to the rod, which would have saved me making the template plug. Clever bugger.
You can do some real work on that Chinese lathe. I suspect if you did go for that or the second hand one, you would be glad later on but really there’s no way you can tell until a year down the line and you see what you want to do. tough choice.

OK.... So a huge engineering auction is now happening in my neck of the woods. Lots of big lathes. But too big?

http://www.graysonline.com/lot/0014-...lathe?spr=true
A whole bunch of AL-1440s.
2.3kw motor, with 10 amps all I have at home running at 240v I might be able to run it with a VFD from ebay?
720kg doesn't sound too heavy to move around with a trailer and crane, which is what I'd need for 500kg anyway.
They'd be in decent nick at a college I guess?

Edit: Pretty sure I'll get one of these if I can.... So long as I can get a 3 phase converter to get it to work (I've heard ebay, $500?)... It will limit the options of where I can put it in the house but I have enough room downstairs.

Originally Posted by j3dprints

OK.... So a huge engineering auction is now happening in my neck of the woods. Lots of big lathes. But too big?

http://www.graysonline.com/lot/0014-...lathe?spr=true
A whole bunch of AL-1440s.
2.3kw motor, with 10 amps all I have at home running at 240v I might be able to run it with a VFD from ebay?
720kg doesn't sound too heavy to move around with a trailer and crane, which is what I'd need for 500kg anyway.
They'd be in decent nick at a college I guess?

Edit: Pretty sure I'll get one of these if I can.... So long as I can get a 3 phase converter to get it to work (I've heard ebay, $500?)... It will limit the options of where I can put it in the house but I have enough room downstairs.

Likely a good choice if they're in reasonable condition. You're now out of the bottom of the market machines.

Check with Grays and if possible the people on site about collection/removal. Sometimes it's a major hassle and everyone sticks to Grays rules like a limpet. Other times, they're a lot more flexible. It really pays to inspect and talk to the people. I bought a horizontal boring mill at a TAFE auction & didn't collect it for 6 weeks as the TAFE storeman was about to shut the place for the summer holidays and didn't want the hassle of getting it ready, then was happy to work with me about collection when he got back.

PDW

Originally Posted by sacc51

I see the anti Chinese brigade and bottomless pocket brigade have chipped in their usual.

Bollocks.

Jordan

Ditto.

That AL1440 is 415 V according to H&F website, you really need to have a look and see if it is a star or delta motor.
Others here are far more experienced than me to explain the significance of this.
Probably easier and cheaper to fit a 3 hp 240v motor and a 240v suds pump

Originally Posted by shedhappens

That AL1440 is 415 V according to H&F website, you really need to have a look and see if it is a star or delta motor.
Others here are far more experienced than me to explain the significance of this.
Probably easier and cheaper to fit a 3 hp 240v motor and a 240v suds pump

If you can get one with the same frame size or there's enough space for a different motor size to fit. Dunno, probably not an issue but with some lathes, it sure is.

You'll get more vibration with a single phase motor. Whether this feeds through to the work will depend on a whole raft of factors, but it is an issue. Whether you're doing work fine enough for it to matter is another one of course. A lot of lathes isolate the motor and use a toothed belt or similar to drive the headstock input shaft to help keep vibrations away from the spindle.

If possible I'd install a VFD if for no other reason to slow the bottom speed a bit on occasion. Having variable speed is a really nice thing. As the machine is an import and almost certainly also exported to the USA I'd bet it's got a star/delta motor on it.

PDW

Thanks, this is a big deciding factor, I have some reading to do on 3 phase to 2 phase - could be a deal breaker. Any idea on a rough worst case cost?

Any idea on two other costs:
Price lathe will go for?
Transport? I'm about 20 minutes drive away, I was going to hire professionals to move it into my driveway. From there I'd drag it down into my 'lair' and manage mounting / lifting. I've contacted Piano movers they had NFI what was involved.

I went looking at H&F today. The 320g and 336 seem like next best bets if this falls through. Thanks again for the advice.

Originally Posted by j3dprints

Thanks, this is a big deciding factor, I have some reading to do on 3 phase to 2 phase - could be a deal breaker. Any idea on a rough worst case cost?

Any idea on two other costs:
Price lathe will go for?
Transport? I'm about 20 minutes drive away, I was going to hire professionals to move it into my driveway. From there I'd drag it down into my 'lair' and manage mounting / lifting. I've contacted Piano movers they had NFI what was involved.

I went looking at H&F today. The 320g and 336 seem like next best bets if this falls through. Thanks again for the advice.

I'd get the 336. Much better lathe IMO. I was at the Parramatta store today & took a look.

I don't really like the tailstock on the 336, it's undersized for the MT3 spindle I think, but not all that likely to ever be a problem as long as you don't try feeding 25mm+ taper shank bits into a workpiece with no pilot hole. I've been known to do that & more.

Provided the build quality of the one you get is reasonable, I think it'd take a while to grow out of one of those. I do think the 336 should be quite adequate for a good range of work.

I didn't like the 320 - no camlock spindle, a funky power feed control on the carriage, combined leadscrew/feed screw, general feel.

As for what something sells for at a Grays auction, your guess is as good as anyone else's. Keep in mind that you need to add approx 30% to your bid price to get to the final price after Grays rip and GST on top. Haven't checked the details, maybe this auction is exempt, better to calculate it before bidding though.

I just decide well in advance what something's worth to me, bid to that point and drop it if it goes over. Another one of pretty much anything will come along sooner or later.

PDW

They have 7.5% rip on this auction which amounts to 18.25% total added to winning bid. I am keeping an eye on the mills. Pity it wasn't Salisbury, Adelaide.

Dean

Is there some catch going to ebay for DROs? The hare and forbes offers seem overpriced.

Originally Posted by j3dprints

Is there some catch going to ebay for DROs? The hare and forbes offers seem overpriced.

That because they are overpriced. Try comparing anything from H&F to EBay. They may have reasonable prices on machines, but not too many people would buy anything else from them. Prices do seem pretty good on EBay at the moment tho.

Dean