Rebuilding a cheap lathe

[Eric S Dunn]

I am an absolute beginner. I've never turned a piece of metal in my life. I've always been a woodchuck.

Recently there were a few parts I wanted machined and rather than taking them to the local shop, I decided to go with the much more expensive option and make them myself. I started looking for a lathe and mill, and wow, the MUCH more expensive route. I don't mind the expense, though, if I end up enjoying the hobby.

I was talking to someone about my plan and he offered me a cheap Harbor Freight 7"x10" lathe that he had and wasn't using. It's much smaller than what I was looking at, but it does seem like a great place to start. I can get some experience with this little thing and then move on to the one I picked out if I find I enjoy doing this stuff.

The machine is in bad shape, though. All the levers are frozen and everything is covered in caked-on sawdust and grease. I am confident that I can clean it up and I found a website that has all the parts available for whatever I may need to replace (Little Machine Shop). There are a few things that I don't know and can't seem to find answers to.

1) Does it matter what I clean all these parts with? More specifically, is there anything that I SHOULD NOT clean them with? I bought some generic de-greaser for the task, but if there's something more appropriate, I'd like to know.

2) Should I coat all the parts in some sort of oil when I put it back together? If so, what kind of oil?

3) Are there any parts that fall into the "well, as long as you have the machine taken apart, you might as well replace the" category? I already plan to replace the belt but beyond that, I'd like to know if there's anything I should go ahead and replace while the machine is taken apart.

4) Is there anything else I should know before I begin this process? At this point, I don't even know what questions I should be asking.

Thanks for you help,
Eric

 

[tominboise]

Lots of guys on here know more then me, but I typically use kerosene for cleaning things like this. Less risk of harming plastics that it might get on. I would oil the parts after you clean them. The ways of the machine should get coated in way oil and everything else in spindle oil (usually a 10 or 20 weight oil - not motor oil).

As far as number 4, make sure you take off rings, watch and long sleeves before running the lathe. Keep yourself away from moving parts.

 

[GrifterGuru]

@Eric S Dunn

Whelp, where to start...

Given it is a 7x family lathe and a small 7x at that, I would look at what you will actually spend on replacing / upgrading / changing BEFORE going down that route.

As lathes go, a 7x can be a daunting prospect if you are not aware of the fundamental issues most people find with them, such as lack of rigidity, lack of power and the restrictive size of them.

That said, they are a good lathe to "cut your teeth on". Not too small, not too big, not exactly cheap, but not expensive.

There are is a laundry list of things you can do with these lathes but the big three are going to a Brushless motor and controller (kits are available), going with an Electronic leadscrew (kits are available) and going with a 16" bedway conversion (New bed/leadscrew/chip-tray).

With the headstock, an upgrade to a 4" flange spindle if it is only a 3" flange, Angular Contact spindle bearings, brass gibs, extended cross slide travel mod, Quick Change Tool Post & Holder (Most go with a wedge gib Quick Change Tool Post).

If you want to get an idea of just how deep some, myself included go into rebuilding / upgrading / modifying the 7x platform, check out this (ongoing) thread on a 7x rebuild I am doing (<<< LINK)

There are a few members on here with 7x lathes, all will say roughly the same thing about headstock bearings, spindle and bedway length.

 

[machinistnoob]

I am an absolute beginner. I've never turned a piece of metal in my life. I've always been a woodchuck.

Recently there were a few parts I wanted machined and rather than taking them to the local shop, I decided to go with the much more expensive option and make them myself. I started looking for a lathe and mill, and wow, the MUCH more expensive route. I don't mind the expense, though, if I end up enjoying the hobby.

I was talking to someone about my plan and he offered me a cheap Harbor Freight 7"x10" lathe that he had and wasn't using. It's much smaller than what I was looking at, but it does seem like a great place to start. I can get some experience with this little thing and then move on to the one I picked out if I find I enjoy doing this stuff.

The machine is in bad shape, though. All the levers are frozen and everything is covered in caked-on sawdust and grease. I am confident that I can clean it up and I found a website that has all the parts available for whatever I may need to replace (Little Machine Shop). There are a few things that I don't know and can't seem to find answers to.

1) Does it matter what I clean all these parts with? More specifically, is there anything that I SHOULD NOT clean them with? I bought some generic de-greaser for the task, but if there's something more appropriate, I'd like to know.

2) Should I coat all the parts in some sort of oil when I put it back together? If so, what kind of oil?

3) Are there any parts that fall into the "well, as long as you have the machine taken apart, you might as well replace the" category? I already plan to replace the belt but beyond that, I'd like to know if there's anything I should go ahead and replace while the machine is taken apart.

4) Is there anything else I should know before I begin this process? At this point, I don't even know what questions I should be asking.

Thanks for you help,
Eric

I'm a big fan of transmission fluid for cleaning up crusty machines. Cleans everything, harms nothing and leaves a nice shine. Kerosene works well also. As I understand, on those 7x lathes the gears are the weak link.

 

[GrifterGuru]

As I understand, on those 7x lathes the gears are the weak link

@machinistnoob

That is only the case if/where/when the plastic gears are used for the entire change-gear train, though it has to be said, keeping at least one of them in the gear train is a good "sacrificial gear" should a crash occur under power feed.

With a full set of metal change-gears, I keep the main leadscrew gear (80T) as a plastic gear for a "fail safe" weak point.

 

[homebrewed]

Look at that 7x10 as a form of cheap education. With it you can learn the basics of hitting your target dimensions, along with feed rates and depth of cut vs. material types. You also will learn how simple lathes function and what you need to do, adjustmentwise, to get acceptable results. Have fun with it, and if you decide you like that side of things then step up to something bigger/more capable.

BTW don't use diesel fuel as a substitute for kerosene when cleaning up the lathe. It smells. The "deodorized" kero sold for heaters and lamps is better in that regard.

 

[markba633csi]

I like to use Coleman fuel as a cleaner- evaporates nicely, low VOC
In fact, a good technique is to get a shallow foil pan, lined with newspapers, then brush all the gunk down.
Let dry for an hour or so, then pull out the grease soaked papers and toss them- presto, clean machine

 

[pontiac428]

Just for the sake of health, avoid using fuels as a cleaning tool in the shop. They're made to be burned and are stinky, toxic, and full of garbage that the refinery can't sell for any purpose other than setting on fire. Instead of kerosene, use mineral spirits. Instead of white gas, use naphtha. Those are more refined for use as solvents, don't stink, and won't kill your liver as quickly from inhaling vapors or soaking into your skin. There's really no money to be saved for the quantities we use in the home shop anyway. That's my PSA for the day, I hope your project inspires you!

 

[GrifterGuru]

target dimensions, along with feed rates and depth of cut vs. material types

@homebrewed

Feed speed is either the maximum possible stock reduction using the change gear system, which is still fairly high, or by manually travelling te carriage.

Finish itself is partly down to the lathe and the lack of rigidity, especially when not bolted down. Most work, unless within an inch or two of the chuck will require tailstock support and even then, a travelling steady is always advisable on anything over twice the stick-out of the stock diameter (within reason) to avoid stock flex under cutting loads.

As for DOC, at 400 - 500 RPM I have gone as deep as 5mm when hand feeding the carriage and using CCGT insert tools, not that I would recommend it, but I know I can go that deep to run up to a shoulder over a short distance.

 

[Jake M]

I was talking to someone about my plan and he offered me a cheap Harbor Freight 7"x10" lathe that he had and wasn't using. It's much smaller than what I was looking at, but it does seem like a great place to start. I can get some experience with this little thing and then move on to the one I picked out if I find I enjoy doing this stuff.

The machine is in bad shape, though. All the levers are frozen and everything is covered in caked-on sawdust and grease. I am confident that I can clean it up and I found a website that has all the parts available for whatever I may need to replace (Little Machine Shop). There are a few things that I don't know and can't seem to find answers to.

You've got two different double edge swords going on there.
The first being that making the first project on the lathe into a "finished" product is really putting the cart before the horse. Lathes (any lathe) works best after you learn it's character. Unlike wood, these see a LOT of cutting forces, so stuff "moves". Tool selection and/or grinding is equally as important as wood turning, but ten thousand times more options (give or take...).
The second one being that the little mini lathes are inherently made "just good enough", and sometimes not even that. They often need a lot of lovin' to get them up to a standard that will allow you (not the lathe) to make decent parts on. (Or even good to excellent parts, I'm not knocking 'em that hard at all). Many owners find that it takes more investment to bring the lathe up to the standards they want than it did to buy it new in the first place.

Should that stop you? No, absolutely not. But you've got to keep both of those things in mind. For a test thing, to see if you're interested, you've got a great thing there. You've just got to have reasonable expectations, otherwise you're gonna spend an hour with it and loose all intrest in metalworking.

1) Does it matter what I clean all these parts with? More specifically, is there anything that I SHOULD NOT clean them with? I bought some generic de-greaser for the task, but if there's something more appropriate, I'd like to know.

Kerosene or WD40 (which is very kerosene like) work well.
Degreaser like simple green/purple power/ one of those things? Those are pretty fine, they're well safetyfied, but you wanna be able to rinse stuff after. By that, I mean a clean damp rag to follow the cleaner, dry, oil.....

2) Should I coat all the parts in some sort of oil when I put it back together? If so, what kind of oil?

Yes. Bare metal wants to be oiled. Some oil is better than no oil, and on a machine like that, where it can be made to work fine, and even if you do get after that and make it "perfect", it was never built to be an heirloom piece, that advice alone might be plenty good enough. If this is an incidental sideline for you that will get used some, or even if it turns out you use it all the time, you could do better. The first is to stay out of anything automotive. That's not your friend here. Tractor stuff too, none of that. An ISO 46 or ISO 68 hydraulic fluid (R&O or AW would be fine) labeled as such, and NOT lableled for tractors, splitters, or any specialty purpose would make a much more appropriate oil for such things. A gallon would last years. And you don't say what woodworking you do, but if it applies, it'd be pretty ideal for metal slides, trunions and mechanisms on wood working machines that specify oiling as well.

3) Are there any parts that fall into the "well, as long as you have the machine taken apart, you might as well replace the" category? I already plan to replace the belt but beyond that, I'd like to know if there's anything I should go ahead and replace while the machine is taken apart.

It's a used machine, at a price point that makes several of it's individual components worth more than the whole thing. While I do very much believe in and practice that approach to repairing and maintaining almost anything... I'm not spending 30 bucks on brushes for an off shore angle grinder that costs 35 dollars to replace. These are not hard to disassemble. Evaluate anything obvious for feasibility, but plan on a second teardown. Several things need a lot of tearing apart to get to, but the whole teardown is not bad enough to warrant precautionary investments until you know what you have.

4) Is there anything else I should know before I begin this process? At this point, I don't even know what questions I should be asking.

Thanks for you help,
Eric

I'd bet that if you take that lathe to pieces, get all of the sticky parts unstuck, get all the sliding parts un gunked and un rusted, and get to a point where you can say that this is possible to piece back together, by then you'll have questions...

One thing I might toss out, if you need tool bits to even try this out- These are very small and light for carbide inserts. There's a high level of convenience in them, but they want faster speeds and larger depths of cut... If it's in your wheelhouse at all, especially to get going and feel it out, I'd grab a couple of high speed steel blanks and grind some basic tools. Or if something came with it, run with that. They all can work, just maybe easier coming up to speed with a ground tool that's dead sharp, than an insert tool which won't be.