All You REALLY Need to Know About Mini Mills

Very good information. Thanks for making this video!

..."You can't return your purchase if your package has opened or has used"

I wish these companies would make an old school manual shaper. Even an idiot like me could figure out how to make keyways and dovetail slides.

I have an Optimum MH-28V, which looks very similar, casting wise. The Z height seems decent to me, hasn't bothered me too often, it's way more often the Y travel that trips me up, and makes me want a turret style mill.
Mines geared, but the noise isn't that bad. Low gear, high motor speed is a bit noisy (still quieter than the lathe), but if I'm needing that much spindle speed, a lot of the time I can just go to high gear. If I do need to stay in low gear with that much rpm, then the cutting is probably making more noise than the gears.
I do wish it had a bit more torque though. Sometimes, with the variable speed it will start over reving a bit to make up for lack of torque, even in low gear if using an annular cutter or something.

Nice video. On z-height, the trickiest situation for me is using a reamer. These are very long and typically don’t fit in a collet.

Dunno why i watched this video. I have my mini mill, basically same model, just NOVA brand, love it, only motor direction control is with extra step, cant just toggle that switch - everytime, after direction change, need to push ON button, because circuit is very basic. I love metal tools, lovely content.

PSA sticker spotted.

Pure acid test for all mills. Trammed, then a cable is attached to the highest point of the mill head and the father forward stable part of it. A strain guage is attached to to cable and a steady force is applied, pulling the cable laterally towards the end of the bed. Then standard measurements of deflection on two axis can be measured in grams. Just this primitive measurement will give a good idea of how much deflection a cutting bit will apply to the mill which in turn gives you a bottom number of the accuracy you can expect.
A heavier Bridgeport like in your shop can take 200-500 grams before significant measurable deflection. Mini mills - good luck getting up to one ounce.

i really appreciated that you were fair & balanced re: taiwanese/chinese machines. i've seen a lot of videos where people immediately get absurdly racist, so it was a nice change.

great video !

The real decision is crank handle vs. CNC. Manual mill-drills, mini-mills, and yes that venerable hulking Bridgeport, are yesterday’s tech. Before you commit a bunch of money to one of these boat anchors, look at what’s available in the land of hobby CNC.

What is a mini mill??????......certainly not anything that is like a Bridgeport.

as Positive critique, you should add a DISCLAIMER of some sort. Not only would it increase the value of your videos content, it speaks to the credibility of this platform.

For the love of Christ compels us, because we judge thus: that if One died for all, then all died; 15 and He died for all, that those who live should live no longer for themselves, but for Him who died for them and rose again.

16 Therefore, from now on, we regard no one according to the flesh. Even though we have known Christ according to the flesh, yet now we know Him thus no longer. 17 Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new. 18 Now all things are of God, who has reconciled us to Himself through Jesus Christ, and has given us the ministry of reconciliation, 19 that is, that God was in Christ reconciling the world to Himself, not imputing their trespasses to them, and has committed to us the word of reconciliation.

20 Now then, we are ambassadors for Christ, as though God were pleading through us: we implore you on Christ’s behalf, be reconciled to God. 21 For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him. 2 Corinthians 5:14-21

Always chose Taiwan!

So, should I buy a PM30V? LOL

As long as it beats a file it's got a purpose, really.

Don’t buy a milling machine with a Morse taper

Had a lowly 25mv for about 5 years, and in that time the pos paid for itself several times and allowed me to buy a better machine.
It's also a great to make all kinds of mistakes that would hurt a lot more on expensive equipment.
Just be prepared for a lengthy setup and a lot of grief, since even a little bump with throw it out of alignment in it's stock form.
Everything is fixable tho, just don't go crazy on the upgrades. They get quite pricey very fast.
Still use mine as a dedicated precision notching machine, so yeah ultimately I think it's a good buy.

Question, you said that round column mills are inferior to a square column type can you explain why this is so?

i hate mine, i love mine... i guess mines the bigger sister. HM45...46?

it works, but i spent a bit of time learning its idiosyncrasies?

being left semi exposed for a few years wasnt the best thing for the bearings... box got water in it.

so stripped it down and thats when i found the major issue, that one of the gear shafts has a nasty big crack in it along one of the keyways. from the factory judging by the grinding marks... bit hard to select one speed and i know that one day its going to have to be stripped down and remade... at the same time, see if i can beef it up a bit as well.

in this country we have a monopoly of one seller/importer and theyre not interested in after sales support... not even really interested in pre-sales support, lol. a reputation for "customer service" but what can you do given no alternative but bend over and take it?

the big challenge will be when i finally get motivated to start scraping it... gotta love the "decorative" factory scraping... it still has the cutter marks on some of the ways!

not hard as such, just tedious and some parts weigh a bit.

i still cry about letting a bridgeport go years ago as i didnt have the shed for it (remember that bit about "semi exposed"?)

Typically electric motors have the most torque at low speeds and lose torque as they speed up. (gearing and belts aside)

Right to the point, well articulated, great video.

Great content. Thank you.

I'm looking at mini mills. This helped a lot. Thank you.

Have a Taiwanese round column mill/drill for more than 20 years. Back then there was no square column ones. Main drawbacks is the round column and belt changing of speed. On a round column you can't move head up or down without loosing precision. So you have to set height for the longest tool to use before. And have quill down much for the shortest tool. Speed changes takes lots of time, so rarely done. A gearbox may be noisy but you gets lots of torque on low speeds. Fitted it with quill and X/Y DRO and VFD speed control.
If I ever should buy a new mill, it would be a geared square column one with 3 or 4 axis DRO. Finding a used knee mill in decent condition is almost impossible.

Based on my research the mill in the video costs $3700 and therefore it is already a better one. Looking for a cheaper mini mill that is rigid enough for milling iron and steel I found the Sieg SU1 horizontal and vertical universal knee mini mill for approx half of the price. This mills is a very rigid one and I´m very satisfied with it. If the Z-Axis travel of 205mm is enough for your applications, this is my recommendation. I don´t know whether this mill is available in the US, I only found offers in australia and in Germany, where I from.
However, as joansparky4439 states below, you have to do the finetunig prior the first use. Especially the Z-support needs a precise adjusting of the dovetail and the spindle. After that is done the mill works smooth, quiet and with impressing results.

Slave built junk, pass

Very measured and sensible analysis, mate. All the more credible, as you don't seem to be short of 'proper' machine tools in your shop. All in all, a really good explanation of what's what (also the style of presentation was very easy to watch too); New subscriber incoming. 😉

The only thing I'd take very slight issue with, is the advice to definitely avoid round column mills.

I'll grant that new, they're of questionable value, compared with the larger benchtop mills that are available from quality importers like Precision Matthews. However, used, well cared for Taiwanese RF/RF clones, manufactured say, in the 90s, can be a very inexpensive way of getting quite a fair bit of rigidity and capability in a benchtop mill.

The main issue of losing X/Y position when changing Z height can be fairly easily worked around. That Lazy Machinist has a good video on the "longest tool technique" to avoid having to change Z height. There are also a fair few videos around, that show modifications that pretty much remove the issue.

Okay, if someone has the money to buy a PM column mill then it's hard to argue with that choice (Precision Matthews is an importer that those of us in the UK would give our right arm to be able to use!😄)

If on the other hand, someone's budget is more limited (and couldn't fit a used knee mill in their shop), I'd reckon a decent used Taiwanese RF30/31 type is probably a better bet than one of the cheaper, smaller benchtop mills bought new.

Eh, just my thinking though, and that's worth about as much as you think it is. 😁

Very good video over all.
A couple things I would add/disagree with.

First of all it is normally not the casting that gets rejected, those are normally pass/fail. It is the finished part that is culled and resold. I had a 16” Grizzly lathe that was so bad even the dowel pins were misdrilled factory seconds!

Secondly I wouldn’t knock the old round column machines tho they are harder to use they have produced billions of good parts for probably 60-70 years.

I wouldn’t consider the machine you were showing a mini mill tho.

Size wise match your mill to your work.
I have found mills run out of capacity much faster than a lathe.

Don’t knock a half size knee mill.

While is is always good to get the stoutest machine available accuracy is much more important, non of these machines are going to take heavy cuts so unless your goal is to just reduce metal to chips just for the hell of it make sure you buy a quality machine.

Cost of tooling is pretty much the same no matter what size of machine you buy(vises are the exception).

Don’t buy too much machine moving big machines is expensive and dangerous.

Don’t EVER pick a mt2 spindle over r8. Morse tapers are mostly for drilling. Bridgeports are the most common knee mill and they run an r8 spindle nose. Tooling is very easy to find

High School robotics team I mentor has a Grizzly mini mill with plastic tooth gears. I assume the plastic gears are for the noise I’m sure. Gears finally broke after many years of use. Online reseller makes replacement metal gears that fit perfectly. They were noisy at first, but finally wore in and became better.

They are all bad. Push off is around .015 to .020 thousands. Any good CNC or Bridgestone Mill will only push off .002 max.

To lower push off add weight to the machines base such as laying it into cement to dry to create rigidity.

To answer the questions you DON'T NEED TO BE IN VISION,

There is one simple rule of thumb: as big as you can fit for as much money you can spend. And a "slightly" used good machine is at least twice as good as a Chinese-machine. We bought a Shizuoka-mill from Japan, a real Ferrari, for the price of a smallish Chinese...

just PCB wayyyyyyyyyyyy it all. :-P

Bridgeport mills are so cheap right now, I have a hard time justifying a mini mill for nearly the same price?

Great video. Very helpful for someone like me trying to figure out what to look for when purchasing one of these. It is a large investment and difficult to find really good advice like this. Thanks.

I’m just wading through what tooling, holders etc I need for an R8 machine. lol

Toys or tools?

I have access to mill and lathe at work, but I don't want to break them learning. and I would like to be able to work on things at home.

Most of my projects are not in need of more than +-.005" accuracy, and are small hobby stuff, experiments, prototypes, simple things for myself, not a business. I need something good enough to learn on that I can move around if needed (even if I have to use a cherry picker or disassemble it into chunks to move it).

It's about learning, good enough, and not being worried about breaking someone else's equipment.

I have been completely happy with my Grizzley 759.

Great video.

Regarding the belt drive versus gear driven heads, it may be worth noting that a gear driven head has significantly more torque at low RPM settings, as the electric motor remains in the optimal RPM range for torque. The belt drive uses motor speed control across high and low belt settings to achieve low RPM. This means that, at low RPM, the belt drive is not getting great efficiency or torque.

Furthermore, the control board for the speed control on the electric motor is very likely to fail. This is because they generate a lot of waste heat, especially at low RPM, and they tend to be made cheaply, with cheap components that do not handle heat well.

This is more important for small mills and lathes than for larger machines, because how much torque you have determines maximum cutter size, or stock diameter on the lathe.

My mini lathe does not have a gear driven head, and it makes me sad. When the control board eventually dies, I plan to attach a motorbike gearbox to the corpse of the thing, and make a DIY chinese frankenstein gear head mini lathe.

Keep your eyse open and be prepared to move on used machines listed for sale is my best advice. FB Marketplace seems to be where everybody sells these days. I had an Arrow 500 VMC and needed a machine for first operations like squaring stock. I found a well used Enco brand RF30 (round column) locally with R8 collets and an Albrecht 1/2" chuck (that was in good shape) for $750 delivered (probably on CL, around 10 years ago). Step pulleys, limited speed range, but useable. Spindle had a few thou of play if you pushed it, but reasonably good and plumb to the table. I've used the crap out of it. I've used knockoff Kurt Anglok style vises and I'd recommend this si one area you don't skimp. They can be found used as well (I've picked up several Kut 6" vises including one machined-on-all-sides CNC variant). Now, I was a machinist/moldmaker/CNC/everything machine trades guy for 20 years so I have more experience in improvising than the average hobbyist, but it is amazing how much you can do with a cheap far-eastern origin mini mill. Just picked up a Supra 10"x54" knee mill (3600 pound monster) with an older CNC Masters control, and it's surprisingly capable, too. Deals are out there.

i got the 727m, with gears. . i full full power on low rpm. i can do 2" facemill cuts in all material. ti, steel, aluminum 2" facemill cuts in all material. ti, steel, aluminum

First video I've seen of yours, this is very high quality content. Subscribed!

Some of the Chinese machines are decent but can be very easily improved