# Hobbyist mini-machine to bench size comparison



## kylemp (May 17, 2019)

I've had to write this out more times than I would like to have, so I figured I'd write it down here so it can answer other people questions and you guys can add to it.

It's a pretty common question for people who either just starting, or moving to a new machine (generally up in size, capabilities and capacity) to ask the advantage and disadvantage questions and what to look for.

I'll highlight what I either know from experience or research, take it with a grain of salt.

*Mini mills -*
Craftex CX600, CX601, CX605, CX611, CX612
https://www.busybeetools.com/categories/metalworking/milling-1/
King Canada KC-20VS-2, KC-15VS
https://www.kingcanada.com/en/products/metalworking/milling-drilling-machines/
Grizzly G8689, G0781, G0758, G0704, G0758Z, G0463, G0619, probably more of these machine codes
https://www.grizzly.com/search?q=(categoryid:480)

I may have some machines (especially in the grizzly set) that shouldn't be considered a "mini-mill" in the way I am thinking. Generally, these type of machines have a price tag under $3000 new, and a direct drive from spindle to motor. They will probably be R8 or MT2 taper spindles, and probably up to 1hp spindle motors (DC brushless, generally speaking). They would be suited to small work, typically in non-ferrous and plastics, but are capable of work in materials such as mild steel (and probably stainless if you're determined and patient).

What I personally would consider advantages to these machines:
 - They are small and light (which also will be a disadvantage in some ways), making them easily movable and a small footprint for basement shops and limited budgets.
 - Dovetailed ways for the Z, and should allow for head tilting (sometimes all the way around) either by pivoting of the Z axis head mount, or in some instances by rotation of the entire column. 

The disadvantages I see are:
 - Very limited travels and capacities of tooling (even a drill chuck and bit combo can make these almost unusable)
 - Very small quill travels, this is made up for somewhat by the ability to move the head in a somewhat accurate manner with reliability due to the dovetailed ways constraining the Z axis.
 - Not rigid at all, light cuts will have to be taken to A) not stall the motor and B) not have massive chatter. For many this is within reason as its just a side hobby and time is less of a concern. Making prototypes with these machines is possible if the materials and operations are kept inside machine constrains. 
 - Due to cost, they are likely to be low on the accuracy side. I would expect that they may cut a slot, but the tolerance of that slot would be sloppy. This can be corrected but with significant time investment.


*Bench mills*

_*Round column style mill/drill (RF-25, RF-30, RF-31 style, many distributor codes).*_

These machines CAN be productive if the expectations of material removal rate (e.g. time spent machining vs material removed) are kept within reason. They have reasonable mass to them for a hobbyist but would not be reasonable for any sort of machine shop (you'll likely never see one in a machine shop). They are a good upgrade VS cost from a mini-mill as they have larger travels and more HP to the spindle, but likely would not be acceptable as a long term solution unless only light machining is to be done. In my opinion these are more appropriately a glorified drill press with X/Y table. They will likely chatter due to lack of rigidity and have no constraints for head movement.
Advantages:
 - Relatively inexpensive (especially 2nd hand) and many available.
 - Much larger work envelope than mini-mills
 - Work well for drilling applications
Disadvantages:
 - Head does not rotate.
 - Not rigid enough for moderate milling
 - Head adjustments have nothing constraining head orientation, meaning that the head can (and will) rotate when moving it up and down if the quill stroke is not enough travel.
 - These machines will always be belt driven which eventually gets irritating changing speeds (I'll cover VFD's later)

*Dovetail style bench mills (gear head)*
RF-45, PM-45, etc.

This style of bench mill is (as far as I know) the last step of machine that can be put on a bench before entering the mini-knee mill size of machine. They are more expensive than all others before but are generally much better quality, much heavier, have greater travels in all directions and have the added benefit of gearheads for spindle speed. They can come in essentially all spindle varieties (R8, MT, BT30) and are likely the best candidate for CNC conversion in a bench style machine. They are capable of most all machining operations (as always, within reason) and if the time is spent to bring them into a higher accuracy range can do incredible work (Stefan Gotteswinter is a good example of this). My opinion is this would be the top tier for most hobbyists as they are small enough they can be disassembled and moved into a basement, and are worth investing time into making them more accurate. 
Advantages:
 - Heavier machine with more rigid construction allows for heavier cutting
 - Gear head spindle speed selection
 - Can be taken apart to reasonable chunks to get into basements, etc. 
 - Good (best of bench size, IMO) candidate for CNC retrofits and many kits available
 - Offered in many spindle tapers (R8, MT, BT30)
 - Reasonable HP motors generally
 - Largest of the table and Z travels
 - Head pivots 360 degrees
 - Frequently have a Z axis motor to raise and lower the head, and sometimes have a reversing switch on the quill travel indicator for tapping operations.
Disadvantages:
 - Still a light machine (generally under 600lbs fully dressed)
 - More expensive and less available used generally

*Options to improve machines:*

*Power feeds* - These are a must if you intend to do manual machining on a regular basis. They are fairly expensive ($3-500 per axis I believe) and almost never come up used, but they are invaluable for surface finish when fly cutting and getting better tool life as they are consistent (ish) in chipload per revolution. 

*Digital readout* - This is invaluable if you have expectations of making accurate parts consistently. They are not too expensive ($300ish for a Chinese version which are plenty suitable for most people).

*VFD for spindle speeds *_- _While this is an option and does work well, there is a moderate cost in doing this type of conversion. You'll need a 3 phase motor and VFD. While you can buy used 3 phase motors online, generaly these are not inverter duty motors, meaning they are not made for this application. While running below the data plate speed (generally 1725 or 3600 rpm) the fan attached to the motor is not creating enough airflow for cooling, which will lead to shortened life of the motor. Longer periods of time spent at lower speeds significantly reduces motor life. Also, unless a high quality motor and drive are used (VERY expensive from a hobbyist perspective) they have very little low end torque. Do not expect to use a Chinese drive and kijiji motor and get 25rpm tapping speeds. It is an advantage to have a machine with gear head or pulley speed selection that can be fine tuned with a VFD as that is a reasonable adjustment to make, but you will not reasonably (or inexpensively) be able to get a motor and VFD combo that will allow 200-3600rpm with good torque at the same time.

I'm sure there are many things that I haven't included in here, I will add to this as I remember them (if you dont use them all the time you forget). If you have one of these machines (or more), please chime in on your experience.


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## Tom Kitta (May 17, 2019)

Going from a mini-mill to a Bridgeport style 40 taper machine or even similar size horizontal is like going from bike to a Ferrari. Its a pain to use mini-mill for even light milling in mild steel. In harder steel machine can flex so much the endmill will skate over the metal to cut (!) The actual endmill / facemill capacity is a lie. 

You can use 3/4 endmill only for "facemilling". Even 1/2 endmill can be used for very tiny cuts. You need to drop down to say 1/4 to actually do something deeper. Machine would be great for precision small endmills but is heavily limited by its very low top speed of just 2500 - retrofit to 5000 is possible but costs $.

Also for tiny endmills the accuracy of the table etc. is starting to play into it all.

You can stall brushless motor when drilling with 1/2" drillbit but you cannot stall it at all when milling.

You cannot upgrade mini mill no matter what you read online. I spent many hours trying. Welded whole exo-skeleton for it. Huge brace for the back. Never get the column that swings to the sides - get solid column - if you really want this machine. 

Essentially mini-mill is only suitable for these that don't have space to upgrade to anything bigger. Given the pricing on BB site going up to CX600 for just tiny amount of money over CX612 is well worth it. 

As of this writing CX612 mini mill is whopping $1600 this is wayyy too much for this class of a machine. Way, way too much. I got and promptly (over a year of pain) got rid of the same machine for $1000 about 5 years ago. I.e. price increased from $1000 to $1600 over 5 years.

CX600 is only $200 more and is 2x as heavy machine. Price... increased maybe $100 or $200 over 5 years.

CX601, CX611 are both twice as big as CX600 but are whole 1000+ more each. 

The only reason to get a lot of these machines is space constrains or perceived difficulty of bringing it to say basement. Maybe add to it new machine alure or availability in the store. Maybe 1ph operation. 

Grizzly prices in many categories are competetive with BusyBee. Grizzly service is excellent while BusyBee freqently has zero. Fortunately they are the same machines so parts from Grizzly fit into BusyBee stuff. KMS also have King machines.


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## Chris Cramer (Nov 8, 2019)

how heavy of a machine would be needed in order to shape mild steel with a mill? I've been doing a lot of research on mini mills and some lighter full sized mills like the cx 600, and the price of some of the larger sized models compared to the sale price of some mini mills is always what gets me. What I keep hearing is that it is well worth it to spend the extra money for the cx 600 and it's higher performance and capabilities; but I don't know how much I really need for my intended use of the machine. I plan on using it to shape decorative ornaments to add to my blacksmithing work, preferably made of mild steel, or perhaps aluminum if I have to.


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## Janger (Nov 8, 2019)

Chris, you're quite serious about metal work. I think you should buy a used knee mill of some sort. $3K ish plus vise & tooling. The size of a CX603. It would be dramatically better than the mini mills and handle whatever you wanted to do. I have a cx600 - it's now mostly just a fancy drill press. Just save up and keep looking at auctions, kijiji, in the forum, post a wanted ad. I know a guy who should sell some mills - right @Dabbler?


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## Janger (Nov 8, 2019)

kylemp said:


> I've had to write this out more times than I would like to have, so I figured I'd write it down here so it can answer other people questions and you guys can add to it.
> .


I don't know how I missed this post Kyle - it's great. Thanks for posting. Add some pictures would be my only comment.


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## Janger (Nov 8, 2019)

Janger said:


> Chris, you're quite serious about metal work. I think you should buy a used knee mill of some sort. $3K ish plus vise & tooling. The size of a CX603. It would be dramatically better than the mini mills and handle whatever you wanted to do. I have a cx600 - it's now mostly just a fancy drill press. Just save up and keep looking at auctions, kijiji, in the forum, post a wanted ad. I know a guy who should sell some mills - right @Dabbler?



https://www.kijiji.ca/v-power-tool/calgary/mint-craftex-knee-mill/1468041918?undefined

maybe...


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## Chris Cramer (Nov 8, 2019)

I agree that It would make most sense now, for me to save up and not get too far ahead of myself by purchasing something unnecessary for me to use before I take the next step towards my goal. The craftex knee mill you posted I see could be a good start, only, the price is pretty high. However like you said, that could very well pay off in the future.


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## PeterT (Nov 8, 2019)

I had an RF-45 style mill that I thought was pretty decent. Its about as robust a 'bench mill' as you can get before stepping into the knee range. It has a decent amount of vertical headroom which can be challenging on smaller mills by the time you have vise & tooling in there.

When we had a meetup at Modern last year, Alex was putting this one through the paces. I believe it is the Chinese but upgraded version of was mine which was Taiwanese RF-4t5 late 90's vintage. Usually Chinese means cutting a few more corners here & there but actually it impressed me. For one thing it was significantly quieter than my RF-45 (which is related to the splined column shaft design, not the gearbox). So maybe there have been net improvements. Unfortunately I don't see it on the website, only the round column. Could be they just don't have a picture, but you could call.
http://www.moderntool.com/products/modern-model-md-930-drilling-milling-machine/

It should look generically like this
https://www.precisionmatthews.com/shop/pm-833t-page/
https://www.precisionmatthews.com/shop/pm-940m/

Modern provided me a couple of references, customers who bought the model somewhat recently & agreed to a phone call. 

Is all about what kind of work you need to do. If you can afford & accommodate a Bridgeport style knee mill, they are heavier & more robust. They are also 2-3X the price of an RF-45 style new, but used machines come up. Sometimes used can be a real good thing & sometimes it can be the source of a new ulcer. depending on your mechanical skills & parts availability. Ideally have someone knowledgeable help look things over.


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## David_R8 (Feb 9, 2020)

@Janger was your CX600 supplanted by a larger mill?


Sent from my iPhone using Tapatalk


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## thriller007 (May 13, 2020)

Thanks very much for this information!!


kylemp said:


> I've had to write this out more times than I would like to have, so I figured I'd write it down here so it can answer other people questions and you guys can add to it.
> 
> It's a pretty common question for people who either just starting, or moving to a new machine (generally up in size, capabilities and capacity) to ask the advantage and disadvantage questions and what to look for.
> 
> ...


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## David_R8 (May 13, 2020)

thriller007 said:


> Thanks very much for this information!!


I agree with some of the assessment but thoroughly disagree with the assessment that they are not rigid enough for moderate milling. 
With my 1980 RF30 clone I have taken serious cuts, .25" in steel using a 3/4" roughing end mill and had entirely respectable results.

With any machine it's important to learn how it operates and how to obtain the best results.


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