Newbie wondering about mill sizes

[loply]

Hi folks,

Been lurking on here for quite a while and thought I'd finally ask some advice. I'm just about to take the plunge and buy myself a mill and convert it to CNC.

Never used or ran a mill before but spent the last year tricking the hell out of a 7x14 mini lathe, which I've enjoyed.

I want the mill for making general household gadgetry, parts for my motorbikes, camera parts and all sorts of other misc things.

I've pretty much decided I want one of the BF type mills as I gather they offer the best quality:cost ratio and are fairly easy to convert. I can't decide to go for the big one (250kg) or the smaller version (140kg).

The factors I'm considering are:

1) The smaller one is cheaper so I could splash out on things like a rotary table and more tooling to begin with. I could get these eventually either way but I'd feel happier buying more things at the outset if I'm saving £500 on the mill itself.

2) I work almost entirely with steel due to availability to me

3) I think if I'm going to the effort of CNC'ing it, then it may be worth buying the larger one (I somewhat regret spending so much time on my mini lathe now, as I'm going to get a bigger one shortly!)

4) I sometimes think having CNC negates some of the advantage of the large mill? Aside from marginally less table travel, the small mill will do everything the large one does (just requiring more passes)...? But a small mill with extra tooling can do more than a large mill with less tooling?

Would very much appreciate any advice or opinions from those who've been down this route already.

Cheers,

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[Fastest1]

Sure the smaller machine will do the work but the larger machine will do it easier and with more rigidity. The tooling is a cost you have to accept and account for. Why dont you just say it like this, after I get the larger mill it will take just a little longer to accumulate the mass of tooling I want. If a person has the space, electrical requirements and initial investment necessary to purchase a large machine, do it. I have never read a post yet about having too big of a machine. Did you convert the lathe to CNC? If steel is the material you will be cutting, the bigger the better.

[Fixittt]

its a double edge sword as you are aware with the lathe.

You got a small one, spent alot of time with it and found its "WEAK" points. Now you have out grown it. But you are moving on to a larger one with more knowledge of how and why things work. This will translate to the larger machine.

Same with the mill. I have 4 to 5 small desktop mills and I had to get a larger mill (manual) to make some parts that the smaller ones just could not do.

in the end, I would say larger mill and gather tooling as required. In the long run you will be better satisfied with the purchases longer. Rather then running into the "LIMITS" wall sooner.

On the flip side, with a smaller mill, you will learn alot about patience and persistence to get something done.

In the end, its your money.......

If your are a patient person, scour the local adds, craigs list...Ebay you can probably find a larger machine cheaper then a new small one......

[Fastest1]

While you are doing the conversion and becoming more familiar with the resources available here and other places on the net. You will find good deals on previously owned (but possibly never used) tooling. Get ready for the fun and challenge ahead.

[LUCKY13]

There is a guy that bought a G704 & got rid of his IH clone mill. SO there are the few that said they have to big a mill.



Your right it is better to have a mill that is outfitted with the needed tooling, compaired to having a bigger one without tooling. But in your case I feel the bigger mill will be worth the expience. The conversion cost, or the tooling cost will not be much different between the two mills. It will mainly be the diff in the cost of the mills.




IMHO just looking at the G704's specs I believe I would go with the smaller mill. The smaller BF mill will be compairable to the G704 Grizzly mill & if you have watched Hoss's build thread of his 704 you will see the machine is quit capable. I dont know if its possible but get a R8 collet spindle if you can. This will help the ridgidity & help make getting tooling cheaper, and easier to find good used tooling.


A bigger mill is always nice, but the budget does have to be considered. After all the price of tooling & software will always cost way more than the mill itself. If it can be afforded then the bigger mill is just about always the better bet. BUt if the budget is tight then getting a machine up & producing parts will just about always pay for itself if one does any work for outside money. If the opportunities show themself, then chances are that getting a second machine becomes very possible because of the money generated from the first.


Ofcourse if only work is done for ones own pleasure & needs then this want happen. Also you have to consider if there is room for more machines, plus will you be able to afford upgrading if you do end up needing a bigger/stronger mill later. If you have to buy once & be stuck with your choice then think about your purchase very much. It may take longer to outfit a bigger mill, but if the finds will be there then it sould be considered.



Another thing that will happen is if its the first machine just the learning curve along will end up costing more because of broken tooling & mistakes/crashes. Start out with cheaper endmills & after getting more experiance move up to better tooling. The better tooling will always pay for itself in performance & longer life, which is also easier on the machine. But breaking many endmills in the beginning is something to expect.



Jess

[pete from TN]

Having owned quite a few different milling machines now, ALWAYS buy the biggest heaviest mill you can afford. I say this specifically because you mentioned you intend to do mostly steel milling. You can mill steel on even a sherline or a Taig but unless you want to spend all day long waiting for a cut that would take a few minutes on a larger mill you will probably be left wanting a larger machine. I once thought as some of these guys that a smaller mill will do the work just take a little longer, well there is more to it than that. A smaller mill will also vibrate like crazy even in light cuts and particularly in steel. It often causes you to break or prematurely wear out cutters due to machine deflection and vibration. You said you want the machine to work on household things and automotive/motorbike parts. Many of these parts will require a bit of travel that will also be lacking on smaller machines. With all of this in mind and many more reasons I will not get into for what you say you want to do with the mill I recommend getting the largest heaviest machine you can afford. Tooling IS expensive but not so much that you cannot buy a piece at a time as you find you need it. The machine purchase initially is the lions share of the puzzle. Sure over the next few years you will spend more than the initial price of the machine on tooling but that comes in spurts and when deals pop up. Do yourself a HUGE favor and find a larger machine assuming you have the money and space for it. Buy it once, cry about the extra cost for a little bit, then enjoy the better more capable machine for a long time, or buy the less capable machine and cry about what it cannot do for a long time. The choice is yours..... Peace

Pete

[loply]

Hi folks,

Thanks for the replies and advice so far, it's much appreciated.

I'm getting into the details of figuring out exactly what to buy and something I'm a bit mystified about is tool holding and what type of end mills to buy.

I was initially considering buying a boxed set of 2 & 4 flute end mills (say 6 of each), but buying 6x R8 end mill holders is fairly expensive, so I thought about buying an R8 collet holder and perhaps one or two end mill holders for the most commonly used ones? Is this normal or am I completely missing something here?

Cheers,

[LUCKY13]

Collets will hold your endmills just fine. Its really about all I have myself. The endmill holders do hold better but its not really needed. WHen it comes to big endmills though its the only way to use one because collets only go up to so big.


The endmill holders are very stout though. BUt a machine this size you will never really see the need for that much holding force. Plus to remove a endmill holder you have to remove it all the way. With a collet you just loosen it & swap bits if you use the same size shank bits & this makes it faster for some setups. For example you can buy endmills of several different sizes that will all have maybe a 3/8 shank so in this case swaping bits would be faster just by loosening the collet. Another thing about endmill holders is they stick out farther so they take up Z axis room, plus any runout in the spindle could be a little worse, or it could even out any runout if it happen to off in the endmillholder the same amouint but opposite side of spindle runout ( very unlikely though).


Have you looked at "The Little Machine Shops" site? They have some end mill holder sets that are priced pretty good & even though there stuff is import brands they tend to have pretty good quality. They also have them seperate so they could be bought one at a time.


You will find though there will be a need for both types at times with different jobs so it does help to have both, but not a must.


Jess

[Fastest1]

Btw, the 1 guy Lucky refers to who sold his large (IH) mill to get a G0704, most likely only did so because IH customer service and delivery is lacking. It was a wonderful mill under the original owner, he died or sold out and keeping up with orders is proving to be difficult. Just read the threads.

[DSpeck]

My recommendation for endmills is that you buy several of a few standard sizes, and hold them with collets. The reason I say don't buy a set is that under CNC, you just make another pass or two, instead of going to the next larger size cutter. That way, you can have extras of the same size in stock, if the one you're using should break. Carbide will last much longer than HSS, but HSS will be cheaper to learn on. You'll only need a few sizes of holder, as well.

The reason I say use collet holders is that they hold tighter than endmil holders (they grip all the way around the tool, not just in one line). They also (usually) have much less runout than the endmill holders, so your finish is better, and your tools wear more evenly, so they last longer.

Just some more considerations for you...

BTW, I also am on the side of buy the largest mill you can afford (or fit in your shop). The guy that sold his IH clone to go to a G0704 did so because of space requirements in his parents' garage - he said nothing about IH, since he bought the clone mill from MTW here in Canada.

[arizonavideo]

It is always a hard call on the size.

I have all three of the mills a G0704, Weiss 30/PM30 and a IH machine.

I really love the Weiss 30 for small things but the IH and the router table are the only CNC so they get most of the use.

You really need to look at the space needed. If you want to do a lot of CNC work and want to box you mill the larger mills take up lots of space about 9' for the IH ,6' for the 30 and 4" for the 704.

If you mainly deal with smaller parts and have time on your side the 704 is a great small mill. The 30 is almost twice it's size and the motor is good out of the box and it really is the last mill a part time hobbyist would need. The price puts it near a RF-45 and it is not really in the same class but with the larger table it has more travel than some 45's but most people go to the 45 because it is bigger. I can't say this is always right, the 30 is easier to use and quieter and made to a slightly better standard.

Just got the VFD on my IH tonight with AC bearings installed and .0001" run out with 3.8k RPM I'm smoking now...

[loply]

I was tempted by a 45 but I seem to have acquired an oppinion that the 30's are better design and better quality, and I seem to gather the extra weight of the 45 is mostly in the massive base, rather than the column where it would matter?

Turns out nowhere seems to have a 30 in stock with an R8 spindle though, have to wait a couple of months for one to arrive, which makes me think about a 45 again, but I'll probably just wait...

Thanks for the advice so far folks, I have educated myself quite a bit on the toolholding front, think I'll buy a few collets and a few endmill holders and consider making TTS type things once I have it CNCed.

[LongRat]

Just got the VFD on my IH tonight with AC bearings installed and .0001" run out with 3.8k RPM I'm smoking now...

Woa, I bet that's a seriously hot setup now. My main turn-off with the 45 is the slow spindle which you have now addressed.
I have to agree with the consensus on the mill size, having a Weiss 30 myself I have been very happy with the choice. I don't think many people would regret getting one if they had the space. Personally I would give up a small amount of rigidity and mass for more travel - this is what you get with the Weiss 30 over the RF45 type. If you are doing mostly steel and know you will never be going too close to the machine's travel limits on part size, I think the 45 is the best machine to go for. For other materials the spindle really is a bit slow.

[pete from TN]

Well I had not offered my input on the RF45 machines because from your initial post you sounded like you were after a BF machine. Now that you say you are considering an RF45 well that is different.

I have an RF45 Lathemaster machine. It is VERY heavy duty for it's size. The only thing that lacked in quality on the whole machine was the paint job which I have since remedied. The machine was and still is a STOUT heavy little mill and I have owned and used it heavily for over ten years now. I can assure you that the column on my machine is both HEAVY and about as rigid as anything you are gonna find in this price range. I have spoken about this many times on here so some here have heard it before. These RF45's are about the next best thing to a bridgeport in your shop. They have good power, are reasonably rigid for their weight, and they can cut steel or whatever you put in there with relative ease. They also have halfway decent travels which can be easily increased with some subtle mods without any major modifications to the structure. I have been well pleased with mine and I have owned quite a few different mills to compare it to including a knee mill. For the price and size it is gonna be real hard to beat an RF45. I have not ever seen a BF30 in person before but it is at least somewhat close to an RF45 in terms of capacities from what I gather. It still does not appear to me to be as heavy duty as my machine. The fit and finish may indeed be better but as I said before there is nothing lacking on my machine that has ever made me wish I had bought something else. When I put steel or stainless in it I do not have to cringe from the vibrations I experienced in other machines. It just cuts and within reason it will cut most materials easily. Once I got it converted to CNC and got the bugs worked out of my system it is a real pleasure to use and run. My machine now sports a two speed belt drive that I custom made and it literally transforms the machine. I wish you could come here and see this baby chew thru aluminum with a half inch three flute endmill. There are chips flying everywhere!! It really is impressive for a benchtop machine.

I know Arizonavideo has all three machines and he is therefore able to make intelligent comments on the three of them. He must like the BF30 pretty good because he seems to recommend it often. Personally I would not take two BF30's for his ONE IH machine with servo control. It would be about the ultimate benchtop CNC short of a BF46 which is in my opinion a machine in another price class completely. If you can afford one of those and want a benchtop mill to CNC that machine would be about the best available right now from what I can tell. If someone offered me a BF30 in exchange for my RF45 I would not be interested. It just does not seem to be as heavy duty. If the abuse I have put my RF45 mill thru over the past ten years of hard use is any indication of how durable and well built it is then I would say I have NO problem recommending it to anyone. It just seems to keep on ticking. It is not perfect but NONE of these chinese machines are so you will have to expect the little niggly bits here and there but as I said mine has served me very well and I would not hesitate to buy another one. Honestly tho if I were to do it again I would try to get the IH size machine. When I bought mine I was not even aware if IH existed.

I think for what you say you intend to use these machines for you are gonna want a heavier duty machine. I might also recommend you to look at a used commercial manual mill like a tree mill or something similar if you have the room. A rigid ram knee mill is a stout machine and generally more rigid than the venerable Bridgeport. Short of that an RF45 is a good choice...Good luck with whatever you choose and post some pics of whatever it is.. Peace

Pete

[hoss2006]

Loply,
Why the need for R8? You being from England will find MT3 tooling more abundant as that's
what most of the European mills are equipped with, R8 is largely a US preference.
TTS will also work with MT3.
I agree with the suggestions to go with a bf30.
Are you looking at Warco?
Owning both an rf45 and a bf20 I can attest to the fact that the bf class mills are very good quality.
I would replace my rf45 with a bf30 anyday. The bf's are a very rigid design that don't suffer from extra bulk.
Being in the UK you can get the bf30 several hundred cheaper than a 45 which is the opposite here in the US.
The bf30 has the same travels, even more z actually.
I've run milling machines for decades and the bf mills have impressed me for their size.
You won't regret getting one.
Hoss

[loply]

Hi guys,

Thank you very much for the advice so far, I'll be sure to post my progress etc in future.

Hoss - I heard bad things about MT tools getting stuck in the taper and requiring hammering out, and I got the impression R8 tooling was more rigidly held. A quick scan on eBay and of my usual suppliers seems to reveal R8 tooling in equal abundance as MT tooling, so I decided that would be preferable. Perhaps I'm totally wrong though? Is R8 any better than MT in any way? Bearing in mind I would almost certainly be fitting a pneumatic tool release system once CNC'ed?

From the specs I have read most of the BF mills available here claim to have a slight bit more travel than the 45 class ones, though I don't really trust the specs, and are the same price usually. The only difference I can seem to be sure of is that the RF's are 50-60kg heavier but that most people say the BF's are "nicer" in some way!

I wish I was within 200 miles of any of the suppliers as I would go visit them to find out myself, alas I'm not! Can't really justify such a trip given the price of fuel these days!

[hoss2006]

Possible sticking would be one reason for using R8 instead too but I've seen people get R8's
stuck too over the years, usually when they spun a holder and stripped the pin wedging it.
Warco carries both mills (WM18 and GH) with the WM18 (bf30) 325 less, for example.
Milling Machines - Find a Quality Warco Milling Machine
Don't know why one machines specs should be more believable than anothers.
Keep in mind some places sell the short table version of the bf30 too, about 425mm x travel iirc.
Why not take a truck, go check them out and come home that day with one, surely that'd be equal to shipping or less.
Just food for thought.
Always better to buy having seen something in person.
Hoss

[loply]

Hoss, that's an interesting point, for the price and hastle of delivery I could think about spending a day with a hire van having a bit of a roadtrip.

Getting the mill out of the van at my house might be a challenge though, I'd only have an engine crane and planks, I'm sure it's possible but a challenge!

Going off topic here but I was starting to think about welding up a stand/table for the machine, I'm going to make my own as I want to integrate it into my existing shop setup. What do you think about mounting four inverted ball transfer units on the table for mobility? I thought this might be the best way to move the machine when required for CNC conversion, painting, etc. Can easily get them with a suitable rating and my floor is concrete.

[loply]

Double post.

[yooooda]

I have purchased the MTW MD001 with the R-8 spindle for a number of reasons. I have a fair collection of R-8 tooling from another mill so I keep my tooling expenses down. The travel really is as huge is it says on their web page. Actually I think the Z spindle to table is closer to 24 inches than the 22 inches they claim.
The top spindle speed is 1920 rpm with the stock 220V motor. The thing is a beast. I think the column must be 300 pounds by itself. It was just delivered recently and I had to take it all apart to get in the basement shop in relatively small pieces. Initial impression is solid. It is a Chinese mill and they are mostly not superior craftsmen yet, but they are trending in that direction.
The mill was available, it has the larget travel in its class, both for size and price range. Everything about it is heavy, even the handwheels. It is solid enough and big enough to handle anything I am likely to throw at it. It is unlikely I will convert to CNC.