Mills...Spindle Speed

[Bill Hime]

Hello Everyone!

So I'm buying a mill. I've read here that most mini mills do not have a high enough spindle speed for what we do. What is high enough and what mills have it other than Proxxon's mill?

 

Please help me spend my money

 

 

BIll

[WackoWolf]

Check Sherline Mills, you can change it to 10000 rpm spindle speed for a cheap upgrade, plus to me there is none better and it all made in the good old USA. 

[Lou van Wijhe]

Bill,

 

A mill's feeds and speeds are to a large extent governed by the material you are working on. Maybe this calculator can give you some insight.

 

Lou

Edited May 2, 2016 by Lou van Wijhe

[Mike Y]

If working with wood and moving the table manually, I have a hard time imagining a need for a high speed. 1mm cutter on pear on 5k rpm gives a super clean cut, why should I spin it faster?

I am a beginner when it comes to milling, would appreciate an explanation from some more experienced members!

[Gaetan Bordeleau]

speed and feed work together

you can use a speed of 500 tpm if you want but the feed will need to be  slower

20,000 is a more accurate speed  because it will leave as smoother finish on a long run

you could probably do molding at a very slow speed but a slow feed would means  it would take 10 times longer to do

The idea is to find a middle speed of a motor which will give a reasonable feed

 

you could go to 50000 tpm for wood or metal but especially with metal, such a speed will throw  metal shavings many feet away if you do not stop it

[rtropp]

Hi Bill, 

I have an older version of the Micro Mark mill that I got on a close out sale.  It has two pulley steps (speed zones): 70-1600 which i use with metal, and 70 to 2800 which I use for wood. 

I have had no problem with milling wood.  As mentioned above, I do need to feed slowly.  But, the parts are so small that slow does not really seem a chore and the parts are very smooth after the milling.  This is my first experience with milling so I don't know if faster speeds would really help that much in creating smoother cuts or saving time.

 

More important for me is the accuracy/precision of the x-y tables and the vertical (z) adjustment. I have experienced some difficulty with the precision and smoothness of movement. With such small tolerances, the slightest wobble, backlash or misalignment will ruin the piece.  Also important are the range of accessories, which, by the way, end up costing as much, if not more, than the mill itself. This is where the Sherline stands out. I had the opportunity to visit their factory and museum in southern California and was impressed with the quality of their tools and range of accessories.

 

I first wanted to see if I use the mill enough to warrant the expense of trading up to the Sherline.  I do use it a lot for milling as will as precision drilling (even though I also have a Proxxon drill).

 

That said, I would be curious to hear the experience of others who have the Proxxon mill.

 

Richard

[Bill Hime]

Hi Bill, 

I have an older version of the Micro Mark mill that I got on a close out sale.  It has two pulley steps (speed zones): 70-1600 which i use with metal, and 70 to 2800 which I use for wood. 

I have had no problem with milling wood.  As mentioned above, I do need to feed slowly.  But, the parts are so small that slow does not really seem a chore and the parts are very smooth after the milling.  This is my first experience with milling so I don't know if faster speeds would really help that much in creating smoother cuts or saving time.

 

More important for me is the accuracy/precision of the x-y tables and the vertical (z) adjustment. I have experienced some difficulty with the precision and smoothness of movement. With such small tolerances, the slightest wobble, backlash or misalignment will ruin the piece.  Also important are the range of accessories, which, by the way, end up costing as much, if not more, than the mill itself. This is where the Sherline stands out. I had the opportunity to visit their factory and museum in southern California and was impressed with the quality of their tools and range of accessories.

 

I first wanted to see if I use the mill enough to warrant the expense of trading up to the Sherline.  I do use it a lot for milling as will as precision drilling (even though I also have a Proxxon drill).

 

That said, I would be curious to hear the experience of others who have the Proxxon mill.

 

Richard

Richard,

Thank you. I was curious about the Micro Mark mill. I did take a look at the Sherline after Wacko Joe mentioned them. I know I read here somewhere it was suggested that 20,000 was needed to cut with precision at our scale. The Proxxon mill's the only one I could find that had that kind of speed.

 

Sherline has a mill and lathe combo package with a large number of accessories for both. It's priced around $2,500.00. Despite that, I'm taking the leap, working the cost into my capital budget for the shop

 

Bill

Edited May 4, 2016 by Bill Hime

[donrobinson]

Hey Bill, that sounds like the package I bought last summer and I love it. As mentioned above the accessories are what really make sherline shine, and trust me you will always want more

[Mahuna]

Hi Bill

 

I was able to pick up a used Sherline mill and lathe with a bunch of accessories a couple of years ago, and I'm extremely pleased with the setup.  I upgraded the mill with the 10,000 RPM package and would recommend it (although it's not absolutely necessary).  One accessory I highly recommend is the Sensitive Drilling Attachment.

[mtaylor]

Bill,

 

Try it once you get it and test it.  If you get acceptable results, then that's great.  If you think a higher speed will help, than the speed upgrade is the ticket.  I have the MM Mini which now discontinued and after reworking the pulleys I can see the difference in milling wood at 2500 rpm and 10,000+ rpm.  When this thing dies, I would go with the Sherline and speed kit upgrade.

[gjdale]

Your gonna be delighted Bill. The Sherline machines are a real joy to use. And buying accessories for them is an endless hobby in itself - one that's bound to keep you broke. Don't ask me how I know..................

[rtropp]

Mark, I think we both have the same, discontinued MM Micro mill (#84659).

I too am considering the Sherlines as replacement but would like to hear more about the 10,000 rpm upgrade to the MM. While it seems to working ok as is, I do not have a comparison to higher speeds so might be interested.

 

Richard.

[MEPering]

Hi Bill,

 

I have a big mill (42" table)  and I have used it for wood before.  I believe it has a maximum speed of 6k rpm.  I use it for metal most of the time, but when I have used it for wood, I have never had to get the rpms that high to do nice, clean cuts.  The real secret is the sharpness of the cutter, the number of flutes on the cutter and the speed at which you feed the wood into it.  You also have to pay attention to the direction that you feed the wood into the cutter, as to minimize tear-out.  I have an automatic feed on mine, but I almost never use it when cutting wood, only on metals. 

 

I have heard great things about Sherline mills though.  I have neither had one, nor have I used one, since my work is generally larger, and thus, a larger mill is required.  But if it were me, I would see about buying one that was a little larger, and more substantial in weight than the Sherline.  I know both Grizzly tools and Enco offer some inexpensive hobby mills, and they are cast iron beds.  This makes a big difference, as the heavier the mill, the more stability you have.  My mill weighs about 2 tons, so it is overkill for model building.

 

Matt

[thibaultron]

In respect to the back lash you mentioned. All mills that we are likely to encounter, have back lash. You need to determine what this is for the feed screws on your mill, and remember to take this into account when using it.\

 

Alternatly you could try to fit it with a digital readout, very expensive, but very accurate.

[mtaylor]

Richard,

 

I'm not sure what the P/N on mine is... but here's a link to a review I did:  http://modelshipworld.com/index.php/topic/256-micromark-micromill-review/

 

It's not an upgrade as such but more of a backyard mechanic kludge.   I took off both pulleys and re-machined them on the lathe such that they fit on the opposite shafts from original.   I hope that makes sense.  If I get some time, I'll pop off the pulley cover and take a picture.

[mtaylor]

Bill,

 

You might also have a look here.. http://www.littlemachineshop.com/default.php  There's a lot of good information there.

 

Edit.. forgot to add this one also:  http://www.mini-lathe.com/mini_mill/Main/mini-mill.htm

Edited May 6, 2016 by mtaylor

[Bill Hime]

Thank you Mark! your input is always invaluable to me. Not to mention everyone else. Oh btw, links to more places to get lost in the details for one with significant OCD is not very helpful, lol!!!

 

Thank you Don and Frank!

 

Grant, appreciate all the help in spending my money, lol!

 

Update; We had to drop an extra $1,800.00 into the shop floor structure to support the equipment coming. So the mill/lathe combo will have to wait til the June billing cycle.

 

Ironically, with that sais, the Byrne's table saw arrived today along with the Grizzly 12" Extreme 5 hp, 220v cabinet saw. kinda the long and short of it! I'll post a pic of the two together..should be fun!

 

 

Bill

[rtropp]

Mark,

thanks for the info.  Re-machining is beyond my skills right now so I will probably stick with the current speeds and just run slower feeds.

 

Thanks,

Richard

[EdT]

Most of the comments here, I believe, refer to spindle speed.  For a given spindle speed, cutting speed varies with the diameter of the tool, or on a lathe the diameter of the piece.  Cutting speed increases with diameter for a given spindle speed.  So, cutting speed, ideally, should be optimized for each individual setup based on the speed of the cutter at the cut.  Small diameter wood turnings, for example, require very high spindle speeds.

 

High spindle speeds on turnings not only produces a finer surface but also reduces torque on the piece at the cut, reducing breakage.

 

I believe the standard Sherline mill is a bit slow for routing wood, thus leaving a rough surface.  Although I do not have the high speed attachment, I believe it would be a good investment.  Would routers and Dremel type tools have very high spindle speeds for this reason - much higher than machining tools like lathes and mills that are basically designed for metal where recommended cutting speeds are much lower.

 

Ed

.

[wefalck]

For cutting/milling wood also really sharp tools are essential. I would use carbide, rather than HSS, milling bits, particularly on harder woods.

 

Otherwise, for our purposes one doesn't really need to be to pre-occupied with cutting speeds and feeds. In professional and production context this is different, where you want to remove as much metal as possible in the shortest time, arriving at the desired surface quality. With time one gets a feeling how much feed you can have for a given cutter size on a certain material. In many cases you would not be able to feed fast enough by hand for the RPMs recommended for a certain cutter diameter.

 

One should also keep in mind, that higher spindle speeds will reduce the life of ball-bearings. Not sure how long the Sherline-headstock will last at 10,000 RPM. Most small machine tools in the pre-CNC age only went up to around 4000-5000 RPM.

[lehmann]

 

I have a big mill (42" table)  and I have used it for wood before.  I believe it has a maximum speed of 6k rpm. .....

 

 

Matt

Matt,

 

I also have a large mill, (clone of a Bridgeport knee mill) with digital readouts.  I also use it for wood, mainly as a overhead router when I don't want to make a router template.  For small work, I'm contemplating building a mount for a rotary tool (Dremel, Proxon, die-grinder, etc) so I can use their high speed for small diameter cutters and engravers. Basically, I would build a plate with a split-hole for clamping to the quill and the rotary tool would be offset from the quill by 4 or 6 inches.  

[mtaylor]

Wefalck,

 

Sherline recommends that this "upgrade" only be done on machines that are well run-in and also to monitor the bearing temperature.  When it gets warm, shut it down.

 

As for longevity.. good question.   I did a mod my (non-Sherline) and so far, so good.  But then, I'm not running it very long at any given time, either.