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advice on purchasing a small mill

advice on purchasing a new small mill

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James fortin17/08/2010 21:38:36
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46 forum posts
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hi i am needing some guidance as of which mill to buy as i am looking to get the ama16v from amadeal and i am doubtful of the rigidity of these small chinese mills. my only previous milling experience is two weeks at an engineering college using a bridgeport vertical turret mill, having seen how solid these machines are i am doubtful that these small machines can take "big" cuts.
 
any advise would be helpfull, if any of you  have used this model or are aware of problems that can arise
 
many thanks
 
james 
Billy Mills17/08/2010 23:54:58
377 forum posts
Hi James,
You don't have to take of everything in big cuts, it's hobby stuff not production. If you look back through previous posts you will see plenty of advice about which lathe/mill to start with. It all comes down to what you want to spend, what you want to make, where you have to put it and how strong the floor is.
 
I would suggest that you go for the biggest and stiffest machine that you can give a home to BUT it is what you want to do with the machine that should decide it. You can do small work in a big mill slowly but you can't do big work in a small mill at all. You might end up buying  something less than perfect as a first machine then graduating to another as you explore your real requirements. The good news is that mills and lathes tend to hold their price quite well.
 
So you might start with a Chinese job and end up with a Bridgie....
Regards,
Alan.
 

Andrew Johnston18/08/2010 09:22:34
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Lucky those who have the time to take lots of small cuts! Generally I'd say buy the biggest mill you can afford, that will fit in the space available, and run from whatever mains supply is present. There is one proviso. If you're planning to machine small parts with small cutters, then the larger machines will probably not have high enough spindle speeds.
 
To put things into perspective a Bridgeport mill is very versatile and R8 tooling is widely available in all cost brackets, but it's not exactly a rigid machine. As a rough guide, in low carbon steel, one horsepower will remove 1 cubic inch of material per minute, which should give you an idea of whether a particular machine will manage the cuts you envisage.
 
Regards,
 
Andrew
James fortin19/08/2010 09:51:58
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46 forum posts
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thanks thats put things into perspective for me.
 
also has anyone had problems with things like wrong graduated dials, lots of backlash in the leadscrews or badly machined ways on their machine, i just want to know how much "improving" i will have to do.
 
many thanks
 
james 
 
 
Martin W19/08/2010 10:53:45
806 forum posts
29 photos
James
 
Below is an extract from a post I made in another thread on this site. Both the units I bought were 'metric' and there were no problems regarding oddities in dial graduations though I have seen reference to this problem on some other imported machines; I think  if my memory serves me correctly they were machines with  'imperial' graduations.
 
Both machines have a small amount of backlash in the lead screws but this is only a thou or so and this is to be expected on any machine; adjusting backlash on either machine is very simple. All the ways that are a 'bearing surface' are clean and nicely machined or ground with the lathe bed being hardened which I regard as a bonus.
 
 
"I bought a small lathe from Chester, the DB7V, and there was no sign of sand or any other unwanted material/debris, the same applies to the mill I bought from Warco. Both of these machines are of Chinese origin and were delivered in a clean and effectively ready to run state. A clean down of the protective grease and slight adjustment of the gib strips on the lathe after a trial run and they are both performing brilliantly. The chuck on the lathe has minimal run out, well within the test limits, using different diameter ground silver steel bars.
 
The support from both companies is, imo, second to none with no query seemingly too trivial. If it had not been for these companies offering Chinese produced lathes then I probably would not have bothered to purchase any machine. The thought of buying a second hand machine, which would have been my only option, with no guarantee, no support, no accuracy report and no indication of usage does nothing but fill me with trepidation. What I now have are machines that were affordable, have a full back up and should something go amiss I have recourse to getting it fixed.
 
Arc Euro offer similar machines but also offer a full pre-delivery service, at a cost admittedly, but still cheaper than Myford. This is not to knock Myford as I would prefer to buy British but at their prices they were totally out of reach. It strikes me that some people are quick to condemn eastern products on the experience of one or two bad press reports."
 
Please note that I am a 'Hobby Engineer' and have limited experience in this field. The normal personal disclaimers apply re associations with any of the companies etc.
 
As Alan says 'get the biggest you can afford or accommodate in your workshop' 
 
Hope the above ramblings help a bit .
 
Regards
 
 
Martin
Lawrie Alush-Jaggs19/08/2010 11:03:31
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118 forum posts
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Hi James
 
As Alan says, there are lots of posts on this topic both here and on other web sites.
I have a Taiwanese Mill/Drill with a 1.5 HP motor.  It weighs 275 Kg and is a nice machine.
I looked at the X2 and the X3 but decided on the machine I have.  I would like a dovetail column because it increases the work envelope.  With a round column you have to imagine and test all of the tools you are going to use in one setting to ensure you don't have to raise or lower the head.  After a while it becomes second nature and is very rarely a problem.
I find Andrew's comment "in low carbon steel, one horsepower will remove 1 cubic inch of material per minute" enlightening.  I had not thought in those terms.
It will be helpful to think about the size of work you are going to do.  It is easy to buy too small or too large. I would really like a Bridgeport or a Jone and Shipman- even a King Rich but I don't really need the capacity.
I often do things with 100x100mm angle and have no problem securing and machining peices up to about 500mm long.
I can comfortable sit a 125mm vice alongside a 150mm rotary table on the table with room to work successfully.
If you are going to be doing 2" scale models then a smaller machine will probably do you very nicely.  If you need a very rare peice that is outside the scope of your smaller machine, you can probably head off to the Tech again.
I beleive it is important to consider the amount of power you consume as well.  A big machine doing small jobs still uses a lot of juice.
You should also consider workshop space, The machine I have requires about 1800mm from side to side and about 1000mm depth.
 
Laurence B19/08/2010 11:12:07
58 forum posts
It might be worth looking at the 'Wabeco' range of milling machines available through Pro Machine Tools (see 'Shopping Partners' link).I bought a F1210E machine eight years ago and have found it an excellent investment.It's not too big so it fits in my workshop.It is very accurate and can take some 'big' cuts when necessary.Pro Machine Tools attend some model engineering exhibitions.
Billy Mills20/08/2010 23:17:48
377 forum posts
 
Hi James.
The 1 cu inch per HP per min is an approximate figure with carbide tooling cutting soft steel. If the Steel is hard then the rate falls by 50%, if you have a soft brass rate increases 300%, a soft Ali would be around 400%.   These numbers are used to calculate feed rate for industrial mills running carbide tooling at an optimum rate for commercial use.

So that implies very rigid machines with very little backlash running  optimaly chosen carbide tips of exactly the right form at the correct speed with flood cooling.
 
So while the optimal machining rate is interesting as a concept to the M.E. it certainly does not apply to the M.E. in the garage workshop with HSS or odd carbide from E-bay with the odd dab of cutting fluid!   Do not worry if you can't get anywhere near the industrial rate, don't push your mill beyond what you are happy with. Enjoy removing the metal at whatever rates your tooling cuts.  Model Engineering is not a race.
 
Hope that you have looked at some of the previous posts, as advisors we are limited by not knowing what you want to machine!   That really is the big variable. I use two machines, a very small  machine for  1-20 mm objects and a much larger machine for  regular sized work.  As Andrew said, small cutters do need to spin much faster than regular size mills. The usual answer to that is to fit a high speed head to the standard size machine which then will allow miniature work to be undertken.
 
When the great day does arrive, how do you start? I would suggest getting a few cheap HSS mills and running them into some softwood targets to start with. Whatever you mill  don't forget eye protection!
 
regards,
Alan. 
James fortin21/08/2010 09:20:39
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46 forum posts
12 photos
thanks i will only be milling small things such as making a small stationary steam engine and brackets for odd tools, and maybe some ss brake discs for my bike
 
i see amadeal get their smaller lathes and mills form real bull machinery but i don't know where they get the ama16v from and i am wary of the quality, (its not a sieg machine )
 
many thanks
 
james
 
Andrew Johnston21/08/2010 10:35:21
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5070 forum posts
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Just to be clear, the 1 cubic inch per HP guide is independent of the cutting tool type. It is based on the energy needed to shear away and deform the material in a given time. The type of tooling will dictate the surface speed of the cut and the depth of cut. Thus there are two different calculations here. One, which is dependent upon tooling type, will dictate the rate at which metal could be removed. The second, which is independent of tooling type, will determine whether the machine has sufficient power to achieve that rate.
 
I tend not to use flood coolant with carbide tooling, especially on the lathe. On the CNC mill I do use flood cooling, but this is mainly to wash away the swarf, not to cool the tool. Carbide doesn't mind running hot; for some of the newer coatings it's a requirement to run hot for them to work properly.
 
While the ME doesn't need to achieve 'industrial' levels of metal removal I susepct that a lot of reported machining issues might go away if more attention was paid to cutting speeds, feed rates and chip loading.
 
As has been stated above the size of mill you need will be dictated by the size and type of parts that need to be machined.
 
Regards,
 
Andrew
 
 
 
colin hawes13/09/2010 15:10:05
502 forum posts
18 photos
Hi James,
Forget about cu.ins/minute, that's for production work in factories.The machine you need for small models is one that is easy to use for the work you expect to do. I have a mini mill from Warco which does most of my work .I have fitted a cheap digital readout to it and am therefore not worried about things like screw accuracy for measuring out  hole pitches  and distances.The right machine for you is one that will cover the area you need to machine and should have a dovetail slide on the vertical axis.I have access to a heavier machine at my local club.
                                  Regards ,
                                                  Colin 

Edited By colin hawes on 13/09/2010 15:12:54

Andrew Johnston13/09/2010 22:27:01
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5070 forum posts
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I would agree that metal removal rates are of most importance in industry. However, the modeller who doesn't bother to learn a little about metal removal, cutting speeds and chip loads is doomed to waste time, get poor finishes and damage cutters.
 
Milling cutters do not  care if they are running on a 0.3hp hobby machine or a 30hp machining centre; if the cutting parameters are wrong they will not produce good work.
 
Regards,
 
Andrew

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