20 Best Mini Lathe Upgrades And Improvements

G'day everyone,

I have owned my import mini lathe (sieg c3) for over 2 and a half years at this point. I think it is a very capable little machine, and considering the price that I paid, the parts that it can produce are very decent. It can even turn steel with over a 1mm depth of cut.

However to get to this point I have had to make several modifications and upgrades, in order to fix issues from the factory, and expand the capabilities of the lathe.

In this video I will be showing you all the upgrades I have done to the lathe over the past 2 1/2 years. Some of the mods I have shown here on the channel before, and they are linked as follows.

Timestamps
0:00 - Intro
0:35 - Bolt The Lathe Down
1:10 - Quick Change Tool Post
2:27 - Replace The Handwheel
3:56 - Carriage Lock
5;01 - Slide Locks
5:49 - Replace The Carriage Retainer Strips
6:52- Solid Tool Post
7;36 - Replace The Chuck
8:29 - Upgrade The Spindle Motor
9:32 - Tapered Roller Bearings
10:36 - Brass Gib Strips
11:26 - Lever Lock Tailstock
12:15 - Tailstock Base Plate Scraping
12:50 - Apron Gear Cover
13;57 - Oiler Ports
14:41 - Top Slide Leadscrew Fix
16;13 - Spring Under Tailstock
16:26 - Level The Tailstock
16;52 - Rebuild The Cross Slide
17:24 - lapping The Slides
18:02 - Conclusion

#machining #minilathe #workshop

[andersgrassman]

Really IMPORTANT is that when bolting down the lathe, an indicator clock should be used as to check that you don't actually bend the lathebed when tightening the bolts. Because this is actually very easy to do! The forces you apply with the fastening bolts to lathe bed are considerable. And it is done at the far end corners of the lathe, so giving the bed a twist is really, really easy. (Do some readin up on the procedure.)

The other side of the matter is of course that bolting down the lathe adds a lot of rigidity, as pointed out in the video. Also adding a big HEAVY steel base as suggested in the video, is a really good idea. Any added mass reduces vibrations. And then bolt that stell base to the bench "lightly" for safety and things like sawing etc, just not to have the whole thing "skating" around on the workbench.


These mini lathes are really way to lightweight and flimsily designed, but it comes with the economy side of things, so doing the above alleviates a lot of the compromise inherrent in the "mini/micro" aspect of these lathes. Always buy the heaviest and biggest lathe you can possibly accomodate! It makes a huge difference!

Even distance between centres is a lot more important than one might realize at first, because once chucks and tooling like drills are mounted, there is so little space left on a mini lathe, that just changing for another drill size is often a really annoying hassle. I'd say length of bed is more important than a quick change toolpost, when it comes to make work easyier

[Motocue]

Great video, I have been a machinist all my life and built pool cues for 30 years. I have been using the mini lathe since it first came out for putting pool cue tips on. I think I pretty much did all them mods at one point. For me my fav was my rear chuck to hold the pool cue shaft. Through the years I’ve made tens of thousands of dollars on the mini lathe . I used to have a portable one that I would set up at pool tournaments and do tips. the whole thing was mounted to a small butcher block cart that I had on caster wheels . the front was framed in with a Plexiglass window and fluorescent light overhead . I also made an extension so I can put the whole cue or shaft in between centers, it was a simple Bolt on with no flex, the carriage never needed go back there just the tail stock. I had some of the best pool players in the world walk up and have me put their tip on .. I wish I could post pics on here. Anyways awesome vid, keep up the good work.

[wk]

A cheap lathe can do accurate work with a few adjustments and modifications.

[kencurtis]

Great video, I’ve been a maintenance machinist for forty years and you learn how to make due with some pretty junky machinery. I own a couple of mini lathes and a mill and have been running then for five or six years as bought. After watching your video on up grades I think I’ll try a few and make my retirement a little mor ergonomic. Thanks for sharing.

[CaptK-pyrq]

Thanks! Just ordered the 8.7" x 29.5" w/1.5 hp brushless motor and a 1.5" spindle bore. I was eyeballing the full-size lathes, but being a newbie, I thought I'd drop $1300 first before I drop $13, 000...we'll see how things go. Thanks again, some very good ideas!

[BirkinIdk]

This is one of those videos I keep coming back to whenever I'm looking to upgrade my machine a bit. On the topic of the gib strips, I made a couple out of brass but instead of a mill, I used a surface grinder. If anyone is looking to do this, all you need is a tilting vise and a surface grinder. I started by tilting the vise to 60 degrees, which I verified with a comparator (there are plenty other ways to verify this without a $10, 000 piece of inspection equipment haha, just what I had available at our shop). With the vise at 60 degrees, I mounted the square stock in it, and brought it to the surface grinder. I simply ground one side down until I had taken the flat off and I was left with a sharp edge. You'll then need to take the part out of the vise, as you can't grip it anymore, and use the maglock to directly fix it to the surface grinder, sitting on the edge you just grinded. Now when you grind the other side, since the part is already laying at a 60 degree angle, you're already going to get a correct angle on the other side. I took material off until I had a general shape of the gib strip, then switched to a higher grit white wheel. I cleaned up all surfaces and simply went back and forth, taking off small amount of material, test fitting it, and repeat until I got a nice fit. Overall it took a while, quite a bit of surfacing but the end result was worth it and I didn't need a dovetail cutter, and didn't have to use our mill. (I mostly did this because I'm an idiot when it comes to milling and I wasn't confident that I could get a good part with the small amount of stock I had available)

[velcroman]

You might consider putting felt into the oil holes. Doing this controls the flow of the oil to the surfaces requiring lubrication. An advantage is that the oil does not “run out” reducing oil collecting crap from your work and helping to generally keep the tool a little cleaner.

[PanamaSticks]

I've been machining over 32 years. You need to slow down your spindle speed and start using some coolant or cutting oil. The blue chip is a giveaway to using too fast a spindle speed. It will destroy your insert tooling much faster than it would normally last. The steel you're cutting will work harden as you cut it, and that will contribute to poor finishes. And the carbide inserts you're using have the wrong geometry for turning or facing. Get to know the cutting speed of the materials you cut in FPM (feet per minute). A quick and dirty calculation for a practical spindle speed when turning is RPM = (4 x FPM)/D, where D is the diameter of the work in inches. When drilling or milling a hole, D is the diameter of the cutter. But I cut the calculated spindle speed in half . Saves drill bits and mills, especially when drilling or milling deep holes.

[musicauthority]

It would be AWESOME if somehow some of your mods were to get to the manufacturers of these lathes. they could do some of them without much additional costs. and the manufactures who did this would sell more of them.

[quisp]

I found this helpful as I am considering buying my first lathe and like all first-timers the mini-lathe seems like the place to start. I have heard a lot of complaints about mini-lathes however and this video confirmed basically all of them. The consensus I have seen is that you will quickly become frustrated with the limitations of a mini-lathe. It would seem from this video that you have had to replace many of the key components such as the fixtures, motor, bearings etc. because they weren't up to the task. Many have advised that it is better to buy a larger lathe that is used. There is greater precision, build quality, and more features over a brand new mini-lathe. Thanks.

[johnkunze]

I'm new to lathe work and just bought a mini mill. I'm an automation engineer and will CNC it soon. Your videos are awesome and I'm learning well. As for your motor upgrade, a $30 20k rpm 500w or greater with static gearing, being a DC version can easily be turned into a variable speed 50-2500rpm full load using a micro controller, an igbt or MOSFET, a hall effect rpm meter and 10mins of novice programming for <$50 not including power. Use an old computer power supply. Usually 2 x 15amp 12v available + some 5v for logic. See Arduino motor controls. If rpm variant from desired, change power! Also it's far more reliable than last year's tech. 💕❤️🖖😇🤗👍🙏, jpk thanks! PS. I want to add an oiler tied into an ifrared temp sensor. $10

[twistedhairball]

I hope you're proud of your channel, It's really good. If there's anywhere near you that cuts stone for worktops and things like that. Ask them if you can buy a cut off slab of granite or marble, they'll probably be happy to drill a few holes in it, and bolt your lathe to that. From the mass and rigidity you'll see a massive difference in several ways, stability, surface finish, vibration, chatter. Keep up the great work!

[thedownwardmachine]

I don't have a lathe or a mill, and I've never done any machining. For some reason I just find this video very soothing.

[Bimmer_MD]

I cut a dovetail into a right angle plate to mount to the cross slide, then mounted a t-slot plate to the vertical face of the right angle plate in order to use it as a horizontal mill. It worked out perfect to cut the new gib strips and carriage retainers. The next thing that I'm looking for is a good way to be able to adjust the angle of the top slide faster

[mavamQ]

Great mods, makes me wish I didn't sell my mini lathe in expectation of buying a better lathe. I have still not bought a new lathe and I miss having the old one.

[greggv]

An easier fix for the top slide leadscrew is a washer. Find a flat washer with a hole that fits closely over the screw and has an outside diameter at least as big as the bushing. If it's larger, put it on a bolt with a nut to hold it against the head, then chuck the bolt and turn the OD down. Drill two holes through the washer where the bushing mounting holes are. Counterbore the slide face of the bushing so the collar on the screw sits barely below the surface. Replace the two screws with slightly longer ones when putting that back together. This mod loses zero travel forward and only as much rearward as the thickness of the washer.

The best mods cost nothing at all. The easiest is to take the cross slide bushing off and remove the paint off the end that fits against the carriage. Instant backlash reduction. I further improved it by facing that end of the bushing until there was next to nil clearance for the collar on the screw.

Another no cost mod is removing everything from the bed, mounting it upside down on a mill, then cutting the feet bottoms so they're flat and at the same height. That greatly simplifies shimming when mounting to a bench so there's no twist or bow.

There are two factories that make these 7" lathes, SIEG and the better one. The better one's saddle is rectangular instead of "H" shaped so it's very easy to add a carriage lock, just drill a hole where you added that piece of steel bar. The better one has a slightly thicker apron and dual ball bearings on the carriage crank VS a plain hole on SIEG's. SIEG uses (or used to) three bolts to mount the headstock to the bed. The better one uses four. SIEG doesn't have oiling holes in the leadscrew bushings. The better one has oil holes with countersunk openings. One more thing the better one has over SIEG's is on the right end of the lead screw there's a special nut with a threaded insert to take up any endways slop. Put a thin brass washer on each side of the bushing and that can be tightened to zero slop. This company also offers hardened and ground way surfaces if the importer wants that. Lathes with that get a label put on the right end of the bed. The company that's not SIEG uses a nice Pulse Width Modulation motor controller. SIEG tends to not do a good job finishing the bottoms of the bed feet where the other company at least does a cutting pass, likely with a big fly cutter.


My first metal lathe happened to be one of these better versions, bought from a company called Homier Mobile Merchants. They ran a fleet of semi trucks around the USA, setting up shop here and there to sell all kinds of imported stuff from China. Where places like Harbor Freight sell a SIEG 7x10 but that 10" is between plain centers, the one I got was advertised as a 7x12 and that 12" was between a center in the tailstock and the face of the stock 3 jaw chuck.

SIEG has somewhat improved the quality of their 7" mini lathes. My second lathe was a 7x10 from Grizzly with their serial number 346. It was likely from the very first batch they imported. Previous owners had abused the poor thing in many ways, most likely due to its many 'built in' faults. The underside of the ways weren't parallel to the top side, not even in the center. I was able to correct the outer part on my mill but I didn't have the tools to fix the inner part, but since nothing but the tailstock clamp used that it wasn't critical. The motor controller was a very primitive SCR chopper style and one of the main power resistors had gotten so hot it unsoldered itself at one end. A quick hit with a soldering iron had it going. By the time I was done correcting all its problems I almost liked it more than the longer one from the other factory. I thought about getting a PWM controller for it but never got around to it.

[smartypants]

The cutting finish says it all. Impressive machining.

[canadianavenger]

I did mention this in your mill upgrades video, but I'll mention it here too, as it's more on-topic. Adding an Electronic Lead Screw [ELS] is a great upgrade, especially of you do a lot of thread cutting, but also handy for controlling feedrate for better surface finish. As a bonus you get away from having to constantly swap the change gears in and out. Speaking of change gears, the quality of the factory ones is pretty terrible, and the plastic ones tend to crack and break pretty quickly, I recommend getting an after-market metal set.

[Rusty-Metal]

I just saw this in person at harbor freight. Omg. I never understood how tiny she is. How cool. Young made some amazing things on this size lathe!

[achmadosman]

You can at a pinch use your lathe as a milling device. Buy a small milling machine vice and fabricate a bracket to mount it on its side to your toolpost. Mount the mill cutting tools (non tapered ) into the lathe chuck. Your biggest challenge will be to ensure that the toolpost mounted vice is perfectly perpendicular to the lathe . Crude but does work..