Mini Lathe 3HP Motor Upgrade..... (Yep 3HP)

G'day everyone,

In this video we'll take thing up to 11 with the mini lathe by giving it the most powerful motor that I could find that would sit behind the lathe. That being a 3HP/ 2.2kw motor. To put that into context, that is 6 times the power that the lathe came with from the factory, and probably a whole horse power more than the biggest lathe that I have used. Even the big 300mm swing lathes don't come with 3HP. And my goal is to bolt it to a small 7x lathe. (Sieg C3 7x14 Mini Lathe)

If everything goes well, it will probably be the most powerful mini lathe in the world. My goal really is to be able to slow down the lathe so I can properly use reamers adn drills without the fear of burining them up, which is what would happen with the current fixed speed set up.

In this video I will bolt the lathe to a 20mm thick piece of steel plate to add some rigidity to it. I will also machine new pulleys for the new drive belt. I will also machine a new mounting hole for the headstock. I hope you enjoy the video.

#machining #minilathe #lathe

timestamps
0:00 - Introduction & 3 Horsepower Motor
4:17 - Strengthening Plate
5:54 - Machining The New Pulleys
10:19 - Welding The Motor Plate
12:11 - Adding An Extra Headstock Bolt
12:52 - Machining A Pulley Retaining Cap on The Milling Machine
15:01 - Wiring Up The Motor And VFD
16:43 - Test Cuts

[Sanny]

This has to be the most up-graded mini lathe to ever exist.

[davidbastow]

At 3:31 I totally expected you to say "I also can't stress enough how much it feels like a blue monster staring back at me". Those cable glands look like eyes!

[forest]

We should all pitch in and get this gentleman a band saw, I've seen him use a hacksaw in his videos more than I've used one my entire life. Great content 👍

[CraigsWorkshop]

Great work. Got to say it's equal parts fun and scary to watch 😁

One of the more practical reasons to use an over-size motor, is that you can still get ample power out of the motor, even when it's running below rated frequency. This makes the single belt/pulley position a lot more usable than it otherwise would be. Good stuff.

[Steve-lhby]

Nice! I run a 2HP 3 phase on my mini lathe as that's what I had spare. You need to operate the VFD via remote, you can probably use the controls already on your lathe for the variable speed and forward/reverse, it saves having the VFD near the lathe and getting it oily with your fingers. Steve Jordan did a great video on doing it.

[johnathancorgan]

When you did not use a hacksaw to cut the steel plate, I felt a great disturbance in the force.

[gofastwclass]

Wow, what an upgrade! That is like a V8 weed wacker!
I have a 15" swing gear head lathe that weighs 2300 LBS (1043 Kilos) and it uses a two speed, three phase, 3 HP motor. With that much power, depth of cut no longer becomes an issue for the hobbyist. Your new problem will be rigidity and damage if / when you make a mistake.

I love the creative solutions to your problems, thank you for sharing.

[artisanmakes]

Tune in next week for the dramatic conclusion. Already up to 3mm DOC in steel and I can definitely push it further. EDIT: Alright the internet convicted me to change the wiring, no need to comment further. Also the wring is already delta, you can probably see the connection terminal in the top right corner at the 16:36 mark. See you this Saturday

[crazypj]

Love the logic 'three is bigger than two'
Glad you explained why your using carbide tooling, makes perfect sense when you have enough power and can't get low rpm.
I have wondered what would happen with a two hp motor as I just happen to have one, going to three is total overkill but great fun.
For brazed carbide, use a Dremel and a cheap Chinese diamond bit to re-shape top cutting edge for aluminium

[fredflintstone]

Love it!
I own a chinese mini lathe and one of my biggest complaints is the very low torque at slow speeds. I replaced the fuse with a circuit breaker and will overload and trip it when I'm trying to torque up on something at a low RPM. One must keep a meathook on the speed control to pull this off.
It's one of several reasons that I'm on the hunt for a used 'big boy' lathe. Not only can I handler larger parts which has been another problem, I can get higher torque at lower rpm. Of course a motor swap out like this is another solution but I'm going right to a more complete solution to the shortcomings of the mini lathe. Don't misunderstand me. I've made a lot of great small precision parts with mine but if I had it to do all over again I would have bypassed the purchase and saved my money for a better lathe. I've also spent a fair bit of time making improvements to the mini lath.
Hindsight of course always being 20-20.

[PositronicDiscombobulator]

I can't believe I bought the same motor, well a 1.5kw 2hp version. I was thinking about the 3hp one but chickened out.
I fitted it a week ago and I'm loving it, great motor and what a price.

[tims]

I must admit I missed seeing the hacksaw in action when cutting down your 20mm flatbar to length.. I doubled the HP to 1hp on my small scope multi function machine and it made a big difference, 3hp is going to be interesting!

[LitchKB]

Fair bit to discuss here.

Firstly, I have a minilathe as well - maybe slightly bigger than yours (what would be considered a 7" lathe, but has more mass) - I run a 1.5kW 3ph motor - but I wire it in 415v mode ("Star " aka "Wye" configuration) on a single phase 240v VFD - I can tell it's the same as how I saw how you have wired yours, where the resulting power maybe ends up around half that, and this is more than enough to perform huge depth of cuts, but you're still in the "grey area" of snapping cast iron in half if you crash it. DO NOT WIRE IT IN DELTA CONFIGURATION - that would remove all doubt to causing permanent damage.

Next, with VFDs, the lower the frequency, the higher the current draw - now you've wired it in star config - which is a good start as the coil resistance is increased, but you should be cautious of running the motor under 20Hz - there is a small risk of blowing up the VFD (recently happened in a FB group I'm a member of), but that risk is lowered due to the star config and 240v input.

If you read the VFD manual - it should have a "Max current" setting - good to set to the max rated current on the motor's spec plate + 10%, and "Minimum RPM" (Set to 15-20Hz). Max RPM is typically 80Hz before 3ph motors begin being inefficient, but if you're finding yourself at 80Hz and wanting more - you should probably redesign primary the pulley ratio, or add pulley ratio options so it requires a belt change, 95% of your work should be within the 25-75Hz range without any belt change.

Some other VFDs can also display "Alternative RPM" (by using a multiplier against the frequency) - so depending on your pulley setup, you can have it read out true spindle RPM instead of just the 3ph frequency. I never got around to doing this on mine and have come to know it intuitively, but might be beneficial to you if you get this set up before you end up getting used to it, like I have.

With bigger depth of cuts, more RPM, more power - come more heat. It's time to invest in a "mist cooling system". They're $30 on eBay and need a 30psi air feed and (ideally) a source of semi-synthetic coolant mix (or plain water at minimum). It's either that, or you'll continue to burn out your carbide. I'm very much like you in that respect - just preferring to use carbide, never had HSS - but you'll find that has it's limits as well, so do yourself a favour and get a coolant setup going.

Next, consider a diamond wheel setup where you can touch up your tools - a couple of 6" diamond wheels is $150 on eBay (600 grit, 120 grit), and makes for another decent project + learning curve to build the sharpening station and technique to use it, to optimise your lathe work. A properly freshened-up, mirror-finished brazed lathe tool is really something to behold.

Love your work - as I continue my own journey somewhat in parallel to yours.

[mangamaniaciam]

Two things I learned from welding classes: #1- When welding two pieces of steel like you did, grind a groove into both sides before welding to make a more solid weld. #2- Flux spray EVERYTHING to be welded for the most reliable and strongest weld possible!😊

[nbprotocol]

To get slower speeds from a drill press you need to use the spindle of the drill press as a countershaft. I'm doing that, i got a central machinery 5 speed drill press and it has a 2/5 HP motor, better than 1/3 and not as good as 1/2. If you use the spindle as a countershaft then you can gear it down more and get more torque and slower speeds. The slow speed on the drill press is 760 but using the spindle as CS I get half that on the lathe. I had to take the spindle out and turn down the part where the chuck goes to 12 mm then I got a 17 tooth timing pulley with a 12mm bore, that is the same number of teeth as the lathe motor came with. The nice thing about that is that you can use the whole drill press head casting so it's all lined up. Then you just need to come up with a slide for the whole assembly for belt tension.

[jaivenmayvis]

I'd Artisan Makes had a Patron with Blueprints to his Designs/Upgrades, I'd 110% be a happy and loyal customer ! I love everything he does.

[owenclark]

my god. that thing is a real beast now. I have one of these 7x12 mini lathes, but I have never considered going to this level of extreme. I don't think the 42" toolbox that I have my lathe bolted to would be able to handle that level of upgrade.

[lht]

Man, you outgrown your lathe many projects ago. Awesome work.

[richardrockliff]

LOL I thought putting 2HP on my Seig C6 was going to be overkill, however Im thinking of getting a 3HP one now to replace it and using the 2HP for my belt sander im building, thanks for all your videos I never miss one, as your are running pretty much the same kit I am.

[philipgeorge]

Have you checked the alignment of the bed after bolting it down to a piece of 20 mm hot rolled. Just a thought?