Benchtop mill choice (Sherline, Taig, other?)

Hi,

I'm looking for a benchtop mill with a rotary table. It's my first piece of equipment. I have some small projects in mind, but I'd like to be able to make some microphone clones eventually. Mostly aluminum, plastics, maybe a touch of brass, steel and thin CF panels. I don't plan on running coolant.

I'm thinking about starting with a manual mill and converting it to CNC after I get the hang of it. The Sherline units seem very accessible and decent. Is the Taig much better? Please advise.

Thanks!

Especially for aluminium you should use coolant.
I'm using ethanol for aluminium.

...markus

A month ago I ordered a mid-class china one. 40×30 cm table, 500w spindle, ballscrew etc. It is probably rocking on a big boat across the indian ocean as we speak. Ill keep you posted when it arrives.

The small table top ones I have used do not have much x,y, z movement also IMO they need  DROs on the axis's.
Have you ever used something like a Bridgeport knee mill? 
I have not used a Sherline or Taig mill (I do have a Taig lathe and a Sieg  lathe and mill (the mill is still in the crate)at home)
I have used a version of the Sieg X2 mill (makes a nice drill press), and sometimes use  Bridgeports at my job.  One reason my X2 at home is still in the crate.

Have you sen this site? 
http://www.mini-lathe.com/Mini_mill/Main/mini-mill.htm
http://www.mini-lathe.com/Links.htm#Lathe_Vendors

Markus: Isn't there a fire-hazard-problem when using ethanol for machining?

I never tried it because I worry about this - is it not a problem in real-life-use?

Jakob E.

Jakob:
It isn't that hazardous as it sounds, cause only a very small amount of ethanol is needed,
and the ethanol evaporates quite fast.

I never had any problems with it... although I'm a smoker ;-)

But of course, a little caution is not wrong.

...markus

Thanks - I'll try then..!

Jakob E.

I have a Taig. It does nice cuts but is very small. I got it because I thought I could use it for milling and engraving, if I automated it. This is true but you have to move the workpiece a lot of times to do that. So it doesn't work very well. I don't think a Taig would be big enough to do say a U87 body. But don't take my work for it. I'd check it out.

I want to be able to work on 19" faceplates. They are big. You need at least a 40" table to have access to the whole thing without moving it.  A big vertical mill is not in the cards. Too big, heavy and power hungry. It's hard to know what to do.

Sherline and alike are very small mills. The advantage of Sherline is that you can get it with ballscrews if you intend CNC conversion in the future.

Throughout the years I changed all kinds of mills--micro-mill, mini-mill, heavier Chinese mills with round and square columns. Finally, I stopped with Clausing 8520 knee mill. It is not a bench top, but a little Bridgeport brother--ideal size for a basement, or garage--if you take it off the base two people can easily put it down into the basement. It has a MT2 taper (which used in some Bridgeport heads, as well), but I heard they were also made with R8 heads. This is a very accurate, tight, and reasonably rigid little machine.  Once you learn how to deal with backlash you can totally rely on the dials (including on the knee) until you get your DRO's. In fact, a couple years ago I got Anilam glass scales and still did not install them, because the dials are so good. Unlike Chinese machines these give you perfect square cut, good parallelism, and easy head tramming.

There are some similar mills from Delta, Rockwell, and some European models.  We have in the shop a large few ton Matsuura CNC milling center with ATC, 1.250" ball screws, etc. and still I am using that little baby almost every day...

You don't need to use flood coolant--for what you are doing mister should work just fine. In fact, because it has a pressure air it blows the chips off the way and you get much nicer finish--often we use it with Matsuura, as well...

One piece of advice--don't buy Chinese cutting tools--get only quality stuff--Iscar, Garr, Micro100, Kenametal, Sandwik, etc. They are more expensive (not by much, though) but last much longer, are more precise, and leave much better finishes. You can take much larger cuts with those (but of course, you might be limited by the rigidity of the machine itself). Also, don't try to save on vise--get a good quality biggest one you can fit on the table. Get one with changing jaws--later you might find yourself working quite a bit with soft jaws.

For the rotary table it really depends what you want to do with it. If you need continuous cuts then get a rotary table (Sherlines 4" are good). If you need it just for perfect hole alignment, cutting the grill openings, etc. then I'd recommend an indexer--it is more precise and repeatable, and is cheaper. To get that kind of precision with rotary tables you will need to get perforated plates (and they are expensive).

Best, M

Marik said:

Finally, I stopped with Clausing 8520 knee mill.

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I've seen that Clausing before and it looks nice. Unfortunately it looks like the the biggest table on a Clausing 8520 is 24" which is not big enough to work on a 19" faceplate.  You need at least 19" of travel which brings you to a 40" minimum table.

For that kind of travel the only benchtop I am aware of is Rong Fu RF45 types of the mill (and you don't want to get a round column variations). The pros--it is heavy and rigid, has R8 spindle, can take larger cuts, has a good travel on all axises. The cons--it is not nearly as good quality as American (or Japanese) made machines--I had one and needed to  take apart its head and clean the sand which stayed in the head from casting (just imagine what it'd do to the gears and bearings pretty quickly). Tramming is a nightmare, the parallelism and squareness are questionable (if that's of concern). The bearings are noisy and not accurate, the spindle is slow. But once you know how to deal with all of those and know what to expect it can work for what you need pretty well. In any case, I got rid of mine (and I got it already converted to CNC). For working on panels instead of compromising on the mill I'd rather get some engraver/router type of CNC machine, which usually have plenty of travel and can be had very cheap (I frequently see American made ones for some $400-$600 on ebay). The main advantage is much faster spindle (usually 10,000 RPM), so your engraving will look much nicer.

Best, M

Gold said:

Marik said:

Finally, I stopped with Clausing 8520 knee mill.

Click to expand...

I've seen that Clausing before and it looks nice. Unfortunately it looks like the the biggest table on a Clausing 8520 is 24" which is not big enough to work on a 19" faceplate.  You need at least 19" of travel which brings you to a 40" minimum table.

Click to expand...

Marik said:

For that kind of travel the only benchtop I am aware of is Rong Fu RF45 types of the mill


or working on panels instead of compromising on the mill I'd rather get some engraver/router type of CNC machine, which usually have plenty of travel and can be had very cheap (I frequently see American made ones for some $400-$600 on ebay). The main advantage is much faster spindle (usually 10,000 RPM), so your engraving will look much nicer.

Click to expand...

I'm coming to that conclusion. There is a Bolton Tools version. Square column 40" table. Just not having to move the workpiece would be a big step up.  I wasn't planning on engraving with the mill. The Bolton Tools version comes with power feed and a DRO. That's perfect for me. I want a manual mill. 

I would also get a small engraving table.  First do the engraving and use that to mark and holes, cutouts, ect. Then use the mill to do that stuff.  And of course I'd have a bigger mill for all sorts of things. I'm not that good yet so I think having the mill be a little loose is okay. I'm not doing anything that really has to be within 0.001".

When I have my barn in the country I'll get a Bridgeport.

Gold said:

I would also get a small engraving table.  First do the engraving and use that to mark and holes, cutouts, ect. Then use the mill to do that stuff. 

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But why would you want first engrave and then use the mill when you can interpolate all the holes/cutouts with the same engraver automatically? Just get a collet for an endmill and go lighter passes--in Aluminum the engraver would do all that stuff perfectly fine.

Best, M

How could I make a VU meter sized hole with an engraving table?

You don't always need a rotary table.
You can do Polar to Cartesian for the x, y
As Marik posted a mister is a good idea but be careful of breathing the fumes
If you want a nice finish cutting fluid is a big help
When machining plastics read the MSDS because they can outgass nasty stuff.  This is often worse when you get them hot.
Read look at youtube etc. about Tramming, then look at how some small mills are built.

Marik said:

For the rotary table it really depends what you want to do with it. If you need continuous cuts then get a rotary table (Sherlines 4" are good). If you need it just for perfect hole alignment, cutting the grill openings, etc. then I'd recommend an indexer--it is more precise and repeatable, and is cheaper. To get that kind of precision with rotary tables you will need to get perforated plates (and they are expensive).

Click to expand...

Is an indexer the same thing as a dividing head? I often need to do evenly spaced holes. It looks like it takes some thinking and  calculator to use one of those.

Some look like they have a lathe chuck to hold the workpiece and some look like rotary tables. I haven't been able to figure out the lingo or what the differences, strengths and weaknesses of the different types are. I saw a Sherline stand alone CNC rotary table for $700. That looks easy to use.

Gold said:

How could I make a VU meter sized hole with an engraving table?

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You just tell the program what to do and the endmill will remove all the unwanted material--any shape, any size . If you have Mach 3 there are wizards where you can easily define things even if you don't know G-code.

Gold said:

Is an indexer the same thing as a dividing head? I often need to do evenly spaced holes. It looks like it takes some thinking and  calculator to use one of those.

Click to expand...

The dividing head has more possibilities and number of divisions. You'd be able to make some odd divisions like say, you are making a gear and you need 127 teeth. For the most of work (at least with microphones) you don't need it and indexer works just fine. Most of the indexers have comfortable 5C collets. Those go up to just little over 1" work holding size, but you can get emergency ones, which can go up to 3". You will need to be able to bore those (i.e. you will need a lathe capable of holding 5C--most of the shops will be able to help you with that). We have a Harding indexer, which is probably the best--it can be mounted vertically, or horizontally and has releasing lever. Those come with special mounting plate and tail stock for easy setup. They come with two nose versions: Hardinge 4* taper, or Hardinge thread, which is very convenient, as with special nose adapter you can mount any chuck, as well.

If you have CNC you don't need rotary table/indexer for most of the jobs--only if you do something horizontally.

Best, M

Marik said:

You just tell the program what to do and the endmill will remove all the unwanted material--any shape, any size .

Click to expand...

I guess I thought removing a lot of material with a small end mill would be an exercise in frustration.  The amount of time something takes is important to me. I can't let something go for hours. I don't have the space or the time for that.

I thought getting a light duty engraving table along with the bigger mill would give me more options than getting a heavier duty engraving table with a spindle that can efficiently remove material.  Since I would have to babysit any CNC I might as well throw the piece on the mill and do cutouts and holes quicker by hand. I'm trying to keep this under $10k.

The dividing head has more possibilities and number of divisions. You'd be able to make some odd divisions like say, you are making a gear and you need 127 teeth. For the most of work (at least with microphones) you don't need it and indexer works just fine.

Click to expand...

Thanks, I'll check those out.

Gold said:

I guess I thought removing a lot of material with a small end mill would be an exercise in frustration.  The amount of time something takes is important to me. I can't let something go for hours. I don't have the space or the time for that.
I thought getting a light duty engraving table along with the bigger mill would give me more options than getting a heavier duty engraving table with a spindle that can efficiently remove material.  Since I would have to babysit any CNC I might as well throw the piece on the mill and do cutouts and holes quicker by hand. I'm trying to keep this under $10k.

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Why would you want to babysit the CNC? A good quality carbide cutter can go for hundreds and hundreds of holes, esp. in Al. Just use two flute coated stubby GARR, adjust the air to blow away chips (so they don't clog the endmill), chose right speeds and feeds and leave that baby to do the work and go have tea. The 10K RPM spindles remove material extremely fast, even with 3/16" end mill. It will probably take for you more time setting up the panel to do it by hand than that baby will cut all the holes and idle for the next panel...

A good quality engraver and good quality mill should be way under $5k.

Best, M

Marik said:

Why would you want to babysit the CNC?

chose right speeds and feeds and leave that baby to do the work and go have tea.

Click to expand...

The shop and the studio are in the same space. Running the shop means no studio and running the studio means no shop. I have to be there so getting it done efficiently is important to me.