Metric Lathes in the USA

Hi...

Just out of curiosity, do you need "lathe precision" on these tubes you are cutting and facing? Also, when you say facing, do you mean side cutting or, are you simply squaring-off (facing) the end? Maybe there is some other machine to address this.


As far as Asian lathes that I carry through Precision Matthews, both styles (US and Metric) are based on the same frame, same internal gears etc. The differences are accounted for only by the dials, labeling and the three main screws (lead, compound and crossfeed) in the system. Even the change gears you get will be the same -just different instructions on how to use them.

We recently had a situation whereby the factory sent us a bunch of metric machines and a handful of them accidentally got shipped to customers. The factory is sending a change-over kit (which by the way folks, is due to arrive in PA in about 10 days) which will take about an hour to install.

I'm not aware of any manual, current production machines capable of the bore size you want, with a bed length in the 500mm (20") range. LOL, you could of course consider this http://www.hurco.com/en-us/cnc-machine-tools/turning-centers/lathes/Pages/General-Purpose.aspx but, it might be more than what you're looking for :).

In times past, Matt was able to special order a metric lathe as the request comes-up once, maybe twice every 3 years. The problem now, is the factory has a minimum purchase of 10 units. In the last shipment, he requested 2 units -which was interpreted as 2 x 10 (20 machines) as that's how many showed-up. Going forward, he can order the individual parts but I'm sure there would be terms on the sales agreement.

Ray

EDIT: I fixed an unclear sentence.
 
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David Lewis said:
Hello all!

I want to buy a lathe for my bicycle business, and I have a set of requirements that I cannot seem to find in a single machine, new or old. For the record, I am in the USA.

First, I want a large spindle bore. I want at least a 44.5mm or even better a 50.8mm bore spindle, for cutting off and facing tubing. This is available in a number of variants of new Chinese lathes, and obviously in a number of monster American and British lathes.

Second, I want a short bed. I will never need more than maybe 450-600mm between centers, and anything more than that just takes up valuable floor space. I'll need the room to the left of the lathe for tubing to hang out of the spindle. Are there lathes with beds shorter than 1m with 50mm bores?

Third, I want metric leadscrews and dials. I don't just want metric threading capability, I want metric ONLY! I have no interest in setting feeds and speeds in standard in any way, shape or form. I don't want to have to convert back and forth to standard to make cuts, when all my plans and drawings are in metric. I do not want dual dials unless the system has a clockwork that makes it work properly instead of dividing the metric dial by 25.4. Dual dials may have some benefit if they work like this.

Can someone point me to a product that fulfills the above requirements? The only requirement I can budge on is the bed length, but only somewhat. I don't really want to convert an existing lathe unless it is just replacing the dials, which seems reasonable.
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Hi David,

My $0.02 is you are setting yourself up for frustration with the requirements you've laid out. Getting an affordable lathe with the bore you've specified (also in metric) is, I suspect, nearly impossible.

I understand that facing the head tube and the bottom bracket are essential to making a quality bike frame, but I think you are going at it in a way that leads to big expense with little gain in efficiency. I'm out of my depth as a machinist here, but wouldn't it be far cheaper to cut your tubing over length on a saw, then use a relatively small lathe to face the cut using a mandrel of some kind to support the tube?

After all, the head tube, which is the longer of the head and bottom bracket, is never going to be more than about 9" long, right? Why spend thousands of dollars for a large bore that you don't need to do the job?

If you approach the job in this way, there are many talented and clever machinists on this site who will help find you a way to do the job you need at a fraction of the cost it would take to do it as you have proposed.

Walt
 
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Even a bicycle can be a high precision machine and dials do not provide enough accuracy so you will want a DRO no matter what. The reason for a metric lead screw is so you can use the half nuts for threading. Take a look at the Precision Matthews RML-1440 which does all threads without change gears. It has dual reading dials. The question I have is can you use the half nuts for all threading which would have to be answered by Matt or Ray may be able to get that info faster. No matter what you choose throw in the $800 for a Easson DRO at minimum

Dave
 
dave2176 said:
Even a bicycle can be a high precision machine and dials do not provide enough accuracy so you will want a DRO no matter what. The reason for a metric lead screw is so you can use the half nuts for threading. Take a look at the Precision Matthews RML-1440 which does all threads without change gears. It has dual reading dials. The question I have is can you use the half nuts for all threading which would have to be answered by Matt or Ray may be able to get that info faster. No matter what you choose throw in the $800 for a Easson DRO at minimum

Dave
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In all cases for manual lathes, the "normal" threading style corresponds to the leadscrew. That is, if you have a US leadscrew, the halfnut lever is used as-usual for US threads. ...If you have a metric leadscrew, the halfnut lever is used as-usual for metric threads.

CNC machines are a different matter and to do threading or other synchronized operations, the CNC machine must be "closed-loop" -meaning, there must be a feedback mechanism telling the control software the state of all positions and RPMs. A basic Mach 3 controlled system with stepper motors cannot be used for synchronized operations because, the controller can tell a motor to do something -but, it doesn't necessarily mean the motor does what it's supposed to.


Ray
 
dave2176 said:
Even a bicycle can be a high precision machine and dials do not provide enough accuracy so you will want a DRO no matter what. The reason for a metric lead screw is so you can use the half nuts for threading. Take a look at the Precision Matthews RML-1440 which does all threads without change gears. It has dual reading dials. The question I have is can you use the half nuts for all threading which would have to be answered by Matt or Ray may be able to get that info faster. No matter what you choose throw in the $800 for a Easson DRO at minimum

Dave
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Totally out of my depth here. I don't know exactly what issues the original poster wants solved by using a metric lathe instead of one geared more conventionally.

The OP appears to be interested in constructing bicycle frames by talking about cutting and facing tubing. I'm not certain there are a lot of critical threading operations involved in building a bike frame. Certainly the bottom bracket needs accurately cut threads that are oriented concentrically to the tube. The conventional way that I've seen that approached is to use a special tap and guide. This tool, while somewhat expensive, is part of most frame builder's tool kit.

While it's possible the OP's focus is on single point threading, more often I've seen frame builders use lathes as milling devices to cut miters into the tube ends very accurately to produce closely fitted joints to make strong weld or fillet brazed joints. I'm not sure that a DRO, as useful as it is in general, will help with this.

Hopefully David will return to this thread soon to expand upon what he is hoping to do.

Walt
 
He explained it in original post


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I wasn't trying to be a smart a. I just meant he said he wanted an all metric lathe with large bore


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Walt, I'll chime in on this discussion. I know David personally and he does want metric only threading capability, read that as a metric lead screw. He did mention it on one of his post here, but it is a bit buried and hard to find. David uses a universal milling machine for the miter cuts on the tubing, but wants the lathe for the crank housing and head.

I have been thinking about the spindle bore issue, and it occurred to me that I can pretty easily chuck a 2 1/8 OD tube 4 1/2 deep in my 3 jaw chuck. I have a 13x40 jet lathe. If I needed more diameter, say 2 1/4 inch, I could bore the chuck at least that much without compromising it's integrity. And custom jaws can be built if more grab is needed.

A steady rest would solve the issue for longer tubes.
 
Pardon the length!

As I mentioned, I am a machine tech student, and next year I'll be going to manufacturing engineering school at OIT, if they accept me (I have a 4.0 GPA and GI Bill dollars, so I'm counting on it). I have started a business building bicycles, but I have no plans to be a custom framebuilder, meaning I have no plans to make bicycles one at a time. In addition to the frames, I will be developing prototype parts for bicycles for later manufacturing on CNC machines. Everything I do will be in the metric system, so I just do not want to have to deal with obsolete machines.

This is my company:
https://www.facebook.com/pages/Veteran-Bicycle-Co/236924019838409

Among other reasons, I need the big bore to be able to machine braze-on headset rings from thick-wall 4130 tubing, but I'd also like to use it to make tooling for welding setups, like heat sinks and so forth, and prototype parts like hubs and drivetrain parts. I think 2" is probably enough for the tubing, and that's 50.8mm. It's far more efficient to feed the tubing through the spindle and cut off parts as they're done, but I'm sure I don't need to tell any of you that.

Jim, about an hour ago I did exactly that at ADX. I faced three 1-1/2" headtubes that were each about 6-3/4" long in a three-jaw on an ancient hobby 9-inch Clausing lathe, with decent results. I'm not saying it can't be done! However, I had to hacksaw a much longer tube and then face both ends of each part. That takes away from my beer time, which I would have more of if I could feed a six footer through the spindle and cut off headtubes in the lathe.

Veteran Bicycle Co. will be the recipient of a business development grant though a Portland-based agency, and I need to submit a purchase order soon. I won't tell you how much I'm getting, but I can afford a good lathe. If Precision Matthews can import metric machines, then probably this will be what I'll do. On the other hand, if there are standard changeover kits there must be metric changeover kits I can buy and install in a used machine, right? For all those who wonder, I also intend to install a DRO.

For a while I had visions of buying the kind of tools that new custom framebuilders use, but I have decided to use the summer to build subassembly welding jigs and save my money. I do have some Sputnik jigs for chainstays and seatstays, and I like them a lot, but for some reason they cannot also be used to weld dropouts in, which I take to mean he'd rather you buy his frame jig too. Since I'm not building one at a time, the frame jig is a waste of money to me. I have a 90s-era Henry James jig that will do a good job of jigging the front triangle, since it's just a flat plate with threaded holes.

Sorry if none of you lathe guys care to read about bicycles. Machine tools and two wheels (motorized and non) are all I ever think about, other than girls.
 
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