Looking to buy a new Lathe need some advice.

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Oldtech
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Joined: Mon Jan 15, 2018 9:15 pm

Looking to buy a new Lathe need some advice.

Post by Oldtech »

I asked this on another forum and was directed here...Okay it was more like run outta town for even mentioning an overseas lathe...
Copied from other forum:
I am a retired automotive instructor/mechanic and have experience on automotive lathes/measuring tools etc so I think my learning curve on actual operation won't be too bad. However I have no real grip on the machine's capability/tooling/metallurgy. My intended usage is strictly as a hobbyist at this point.

What I'm wanting to do is have the capability to cut down (lighten, machine off teeth,etc of some smaller automotive gears and machine some one off small parts(likely aluminum) I know the gears are hardened in some fashion but I don't know what kind of tooling and lathe would be needed to accomplish this. I have machined aluminum and cast iron no problem on an automotive brake lathes but not harder steel. Most automotive parts have be hardened in some fashion. I've had this done before but its hard to find shops that want to mess with these smaller jobs.

I've been looking at a couple of new bench lathes. . Grizzly 0602 and Precision Matthews 1030. l know next to nothing about tooling, cutters I might want. Would it be completely unreasonable to think a bench top lathe like this could be up to the task . I'm really not interested in trying to chase down an old american made machine that's not past its prime. I had enough of that restoring old cars. thanks in advance for any input.
John Evans
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Re: Looking to buy a new Lathe need some advice.

Post by John Evans »

You are not going to cut teeth off hardened gears on those lathes ,I would be hesitant to attempt that with carbide tooling on my 18" 5000lb lathe. Basically you will be breaking the edge off the carbide and HSS no WAY! You will need to anneal the gears before even thinking about cutting. Now that said I once removed some hard fine pitch splines on my 12X36 1000lb lathe using .005 depth of cut . Can you say slow?? Ceramic inserts can cut RC 65+ plus material but NO interrupted cuts as the least shock load and the insert is gone.Grinding is a more logical way if you are just trying to lighten said gears. And I don't mean a tool post style grinder either ,a real OD grinder with coolant is what is needed to to do this in a timely fashion. The lathes you mention will be fine for regular work ,you just take lighter cuts. MY personal minimum for a lathe is a 12X36 1000+ lb-er. I have 3 in my shop that fits that description. And I am just a home shop guy.
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Oldtech
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Joined: Mon Jan 15, 2018 9:15 pm

Re: Looking to buy a new Lathe need some advice.

Post by Oldtech »

John that's the kind of information I'm looking for. I did try cutting some of these gears on a brake lathe and the cutter pretty much bounced off the gears and they had carbide bits. I thought it might just be the lathe/tooling not really designed for this type of work. The gears grind easily but I think I'd get more usage from a lathe. I'm just looking to fool around. I had a buddy that can cut them no problem but he's not real convenient. What Lathe specifically might you suggest for a first purchase? Thanks for taking the time to respond.
SteveM
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Location: Wisconsin

Re: Looking to buy a new Lathe need some advice.

Post by SteveM »

I wouldn't be so fast to write off used lathes - looks like you are looking at short work, and mild bed wear won't have hardly a measurable effect on your parts (you can prove that by doing the trigonometry, but it's late and I'm not up to it right now). You can find a used South Bend 9a with tooling for about 2/3 of what the Grizzly costs. Probably with more tooling, and maybe some nice accessories like a taper attachment.

That said, the grizzly on paper doesn't look like a bad deal. Look for some online comments to see how it has worked for those that have bought them. The one things that I have heard is that Grizzly sells similar made-in-china machines that others sell, but their products appear to have somewhat higher quality and their customer service is better.

On the upside, it has a really high spindle speed, which is good for small work, but it doesn't have back gear, so it won't do as well on the low speeds. A SB 9a goes down to 48 rpm and my atlas goes down to 28, while the grizzly goes down to 150.

The spindle is MT4, so I'm not sure what collets you use in it. It has a 1" spindle bore, which is too small for 5C. A 9a uses 3C, the atlas uses 3AT and a SB heavy 10 uses 5C - all of those are pretty common and easy to pick up cheap on ebay or at auctions.

As to machining the gears, it will depend on how hard they are. There is no reason why it should not be able to machine them if they are similar to 4140 pre hard - you should be able to do that with carbide tooling.

If you are talking hardness like rockwell 65, that's another story.

Seve
Oldtech
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Re: Looking to buy a new Lathe need some advice.

Post by Oldtech »

Honestly I wouldn't know the rockwell hardness but these gears are from transmissions circa 1960's. I feel sure they are machinable with carbide bits and the right tooling but I'd have to ask my buddy to be sure. Used lathes are very hard to find here in the south. You are correct in my machining interest would be short runs not far from the chuck. The Precision Mathews peaked my interest since it has similar specs as well as a power cross feed and wedge style quick change tool post ,variable speeds down to 50 rpm for a few dollars more...
RMinMN
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Re: Looking to buy a new Lathe need some advice.

Post by RMinMN »

The hardness of the teeth on the gears is manageable with carbide inserts but it needs a solid cut. Teeth on the gears will be an interrupted cut and each time the cutter hits a new tooth it will be like hitting the cutter with a hammer. The inserts are hard and brittle. Brittle things shatter when hit with a hammer.
Oldtech
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Re: Looking to buy a new Lathe need some advice.

Post by Oldtech »

Yes Sir I can see that.... Many automotive brake lathes use triangular carbide bits and they too are brittle. Maybe some combination of grind then finish would work. I've had gears machined before, and it wasn't terribly expensive once I found someone willing to fool with it. I am still am interested in buying a lathe for other projects so any thoughts on either of the lathes I mentioned or others are appreciated.
earlgo
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Re: Looking to buy a new Lathe need some advice.

Post by earlgo »

If you are not planning to do a lot of gears and the metal removal is not too severe, you could find a person with a tool and cutter grinder or a surface grinder that has some kind of tooling for spinning the gear on a mandrel. Could be as simple as a SpinDexer. That way you would not break inserts or rattle your lathe.
On second thought, a fixture for a bench grinder would take most of the material away and then a touch up on the lathe/ T&C grinder would finish things off.
Just another way of looking at things.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
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NP317
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Re: Looking to buy a new Lathe need some advice.

Post by NP317 »

Addressing your desire to get a lathe for general hobby use, I would recommend a Grizzly machine for a new purchase.
As already stated, Grizzly has been in business since the 1980s and has an established customer service habit that makes parts available for many years. I have visited the original location in NW Washington State several times. They are a serious supplier.
I own a Grizzly G0709 14-40 lathe, and a South Bend mill. I find both machines are superior to a majority of the asian "hobby" imports available today. The mill is certainly equal to the several Bridgeport machines I have extensively used. I can perform any hobby machining I need without spending any time dealing with the machines themselves. They perform as needed. No idiotsyncrocies.

I would recommend you acquire a lathe with at least a 12 inch swing. This will give you a machine with sufficient rigidity to accomplish most hobby goals.
Yes these cost more than a bench-top machine, but you are more likely to keep such a machine long term, due to its usefulness. And not have to fight the machine while using it.
My thoughts.
~RN
stephenc
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Re: Looking to buy a new Lathe need some advice.

Post by stephenc »

I have a grizzly g0602 . I've used the snot out if for just over 4 years now .
I can honestly say it is something that I would buy again . It has been a good solid durable machine that is more then reasonably accurate .
Being a light bench top machine it does have some issues with how rigid it is.
A lot of them can be overcome with just a little effort and no real money spent .
The spindle speed issue can be easily overcome by buying the variable speed version , or saving a couple bucks and converting it to a three phase motor and vfd yourself .

There is one thing I have come to wish I had with the lathe ... and it's not a quick change gear box ( changing gears to thread is quick and easy ) .
The one thing I wish it had ... power cross feed . That is the one single thing that would push me towards buying a different lathe .

You'll hear a lot of the just buy old American iron and be happy arguments , I can agree with that whole heartedly if you know enough to properly evaluate a machine tool .
For those of us who didn't know enough when we started I totally disagree with that .
It's just way to easy to miss potential issues a used machine might have .
You can read threw threads here and on every other forums about guys bringing home a new used lathe that had serious issues pop up after the fact .

One piece of advice I find easy to agree with .... buy the biggest and best you can afford .
Oldtech
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Joined: Mon Jan 15, 2018 9:15 pm

Re: Looking to buy a new Lathe need some advice.

Post by Oldtech »

The power cross feed and the wedge quick tool post is what had me looking at the Precision Matthews too otherwise Id probably only be looking at the grizzly since it seem to have a good reputation and support. Automotive lathes feed both direction so I'm already used to that.

You are exactly right on evaluating a manual lathe. I've probably never been on a good one lol. Mechanics are hard on everything and so are students. The lathes at the college had so much wear the dials were pretty much useless. I relied on sound and feel, Probably not great way to teach..

I don't want to spend a bunch of time working on them I want to use it. I'l look into the larger lathes as well. I don't have a set budget as such but need to weight the cost vrs space and how much I'll use it.
John Evans
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Re: Looking to buy a new Lathe need some advice.

Post by John Evans »

Absolute musts in my book QC gear box-power cross feed -10+ swing -QC tool post. I much prefer gear head lathes to belt change ,quicker and easier to vary speeds. No low speed above 70 or so RPM and machine weight near 1000lbs. Cutting say a 13TPI at much over 70-80 rpm things happen FAST ! Over the last 40 odd years I have owned/operated 6 &12" Atlas ,9-10-14 South Bends-11&12" Logan's and larger machines. Also a fair assortment of Japanese -Taiwan lathes in the 10-14 class.I would say a cabinet mount 11-12 machine to fit my ideas/specs is going to be $4000-5000 new. I currently have a SB Heavy 10-Clausing 5914 12" and a 12' Acra-Turn [Taiwan] + a 18X40 Taiwan. I do like the SB but consider it ,for my use,to be the bare minimum . Only reason I bought it was it has a taper attachment . My thoughts and .05 worth.
John
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