Metal lathe options

[VicHobbyGuy]

Is this sized for your mini-lathe?

They sell different sizes, so yes.

 

[VicHobbyGuy]

Can you squeeze in a bigger pulley on the other end?

No.
A couple of 'extreme users' have posted online about installing much larger motors and re-arranged drive setup, but that eliminates the change gears.

And are there any other intermediate gears that can be revised.

On @Chris Cramer's 7x lathe, the belt connects the motor pulley with a pulley on the spindle. Cogged pulleys and non-standard cogged belt.

The simplest solution- and it isn't entirely simple- to better low speed performance is to use a more powerful, brushless motor. That's a fairly expensive upgrade.

 

[VicHobbyGuy]

It would be interesting for me to be able to use one like that for a while.

Yes, I agree.
But it does take the right attitude.
Most folks expect (rightly) that a tool will work properly 'right out of the box'.
7x lathes are more like a 'lathe kit', which takes many new owners by surprise if they haven't done enough pre-purchase research.
I built a wood-frame bandsaw 'in the days of the ancients' using a Gilliom kit. reinforced it, added a bigger motor, etc.. Used it for years.
Like your use of the 1880s lathe, that sort of thing is not so common nowadays.
It's very strange to me. Look at the price for a 'name brand' cordless electric drill. Then look at the complexity of a 7x lathe, with a startng price of about $700CAD. There would be something 'askew in the universe' if the lathe quality was extremely high. It's amazing to me that they work as well as they do.

 

[Tecnico]

Some skilled 7x lathe users have fitted hand cranks to use for threading coarse pitches.

Count me in, that’s a trick I picked up reading the Myford discussions in a UK forum. I use it for just about any threading I do with my Super 7.

D

 

[Susquatch]

It's very strange to me. Look at the price for a 'name brand' cordless electric drill. Then look at the complexity of a 7x lathe, with a startng price of about $700CAD. There would be something 'askew in the universe' if the lathe quality was extremely high. It's amazing to me that they work as well as they do.

This is a telling observation. If I read it with a blunt attitude, it suggests you think it's not the small size, it's the low quality.

For those that can't afford more quality, it becomes a test of will and patience to satisfy their needs.

If I accept the view you seem to be expressing, then I would prolly revise my recommendations to @Chris Cramer and tell him to go as slow as he can and go with a shallower depth of cut (say 10 thou) and a finer feed rate of say 5 thou per rev) and then adjust faster or slower based on how it cuts.

The tool I ground for him should work at those speeds N feeds. But if I had it to do over, I might have ground a smaller tip radius onto it to go with the lower feeds and I'd have left it full height.

 

[VicHobbyGuy]

This is a telling observation. If I read it with a blunt attitude, it suggests you think it's not the small size, it's the low quality.

Well, exactly. If Schaublin made a similar lathe it would cost $5-10k, I suppose. Even the much, much smaller Proxxon 250 is $2350.

For those that can't afford more quality, it becomes a test of will and patience to satisfy their needs.

And it's a nasty surprise for those who expect a tool - like the cordless drill or chop saw - to 'work right out of the box'. If a person doesn't enjoy 'fettle and fix up' projects, the 7x isn't for them. On the 7x forums people joke all the time that the majority of projects they make are parts and mods for their 7x lathes!

If I accept the view you seem to be expressing, then I would prolly revise my recommendations to @Chris Cramer and tell him to go as slow as he can and go with a shallower depth of cut (say 10 thou) and a finer feed rate of say 5 thou per rev) and then adjust faster or slower based on how it cuts.

The tool I ground for him should work at those speeds N feeds. But if I had it to do over, I might have ground a smaller tip radius onto it to go with the lower feeds and I'd have left it full height.

Yes, those recommendations make sense. The stock .004"/rev feed on Chris' lathe is in the range you suggest.
An alternative would be sharp (not 'for steel') carbide tooling which can handle higher speed. but it's likely that the HSS tool you sent to @Chris Cramer is better quality, so it should stand up to a bit of abuse.
I don't have the stock 250W motor on my 7x any more. If I did (or if I still had my 7x14 Vevor, identical to Chris') and if I had a piece of 1" SS, I would do the experiments myself and report back here.
But I don't have larger SS bar, and I now have a better (800W brushless) motor on my 7x lathe.
My lathe also has quie a few 'mods' to improve rigidity.

 

[RobinHood]

Do you mean shear tools?

Not in the reference I made. @VicHobbyGuy has provided a link in his post #155 to what I was referring to.

I am surprised that you could not make it work, @VicHobbyGuy. I “cobbled one together” with just clamps and other scraps I had lying around and it did seem to work well. But it was not on a 7x lathe…

An adapted version uses the same tool holder geometry, just with round carbide vice the rectangular (square?) HSS it was designed for by the original inventor.

Yes, shear tools are great for taking off very small amounts. I do use them for that as well.

 

[Susquatch]

On the 7x forums people joke all the time that the majority of projects they make are parts and mods for their 7x lathes!

It's a common joke here too. We call it making tools for our tools. I often say that I make more tools for my tools than new tools or parts for other things.

I have just recently discovered sharp carbide inserts. I'm a big fan. But in my opinion, even sharp carbide can't compete with HSS. The thing about HSS is that it is so easy to customize for each individual situation. Also, I don't think you can get a carbide shear tool.

 

[VicHobbyGuy]

I am surprised that you could not make it work, @VicHobbyGuy.

I'm not communicating well today, it seems!
It worked, but it was just 'meh' for me. Not really any better performance than alternatives I was using, and it is sort of bulky and awkward.
But I didn't give it a fair trial, really. It is still lying beside the lathe, in its toolholder, so will probably see more use eventually.

 

[RobinHood]

It worked, but it was just 'meh' for me. Not really any better performance than alternatives I was using, and it is sort of bulky and awkward.

You are communicating just fine.

I did see that you were less than enthused with the tool. (they do claim great things in their promotions…).

 

[Chris Cramer]

Sorry I haven't been around lately, I've been a bit busy with some maintenance around the shop. I just received some new carbide tools and new cutting oil. I don't want to damage these tools like I most likely did to the first few that I used on the lathe, though they still work well. The shanks are 3/8" instead of 1/2" so I'll be able to center them. I haven't tried threading with the machine yet, so Im planning on threading some stainless steel round stock for fastening. I'm confident that the carbide tools will cut the stainless smoother than the HSS; but I still be running it at a lower RPM when threading.

The machine came with a chart of different gear patterns for different thread pitches. I have heard that the lead screw can also be changed to adjust the threading. that might be for imperial threading as everything on the chart is metric.

 

[Chris Cramer]

I made this dial with my plasma table, and etched it with the laser engraver. The numbers are actually very accurate following the readings of the hand held tachometer that VicHobbyGuy mentioned. The dial is 270 degrees and divided by ten for every number. The first 27 degrees led to 200 rpm but every 27 after increased the rpm by 300.

 

[RobinHood]

Steve Summers just released a video where he uses his Mini Lathe to make a part in 6061 aluminum.
He also grinds a custom tool on the bench grinder.
IIRC, he did upgrade his Mini Lathe to tapered bearings. Not sure of other mods he may have done.

 

[Susquatch]

Steve Summers just released a video where he uses his Mini Lathe to make a part in 6061 aluminum.
He also grinds a custom tool on the bench grinder.

I watched it cuz you posted it. It's long and painful, but still a good testament to what CAN BE DONE on a mini lathe. If I can find it, I'd like to see some successful steel turning. Nothing fancy, just real steel.

In hind sight, I should have put bigger reliefs on the tool I made for @Chris Cramer. That way he could have used the tool for facing too and also for a wider range of turning operations by turning the compound. He won't be able to do much of that with what I sent him. I basically only aimed for turning success on 1" stainless bar.

If someone else visits him, maybe they could grind the other end of the HSS tool I ground for him.

Thanks for posting this @RobinHood .

 

[RobinHood]

Thanks @Susquatch.

I should have stated that Steve can get a bit wordy and veers off topic at times & he does show nature shots…

 

[Chris Cramer]

Steve Summers just released a video where he uses his Mini Lathe to make a part in 6061 aluminum.

Yeah, the lathe is useful for fabricating custom hardware/ components. My dewalt die grinder was manufactured with the wrong collet body so it couldn't fit the collets that you buy for this model. The threads on the shaft that hold the collet body are not the same as the correct collet body, so I had to purchase the correct shaft and collet body. However the key that screws onto the bottom of the shaft to link with the motor has a male end as well as the new shaft. In return I had to make a new key with an extended threaded tube to screw to the shaft and link to the motor.

 

[RobinHood]

It takes a tool to make / adapt a tool...well done.

 

[YotaBota]

Steve can get a bit wordy and veers off topic

Sounds like he's been hanging around here. lol

 

[RobinHood]

@Chris Cramer , you probably already found this, in case you have not, here is John Moran, “GadgetBuilder’s 7x12 MiniLathe” website.

GadgetBuilder's MiniLathe and Little Workshop

Minilathe Attachments, Fixtures, Modifications, and Alignment. Plus a DIY Drill Sharpener.

gadgetbuilder.com

He’s got some nice write ups on modifications he made to his machine.

 

[Dabbler]

Summers has one one the cutest Dixon tool holders I have seen!