Small Milling Machine and Accessories recommendation needed

[mmagliaro]

I think narrowminded probably has a very good sense of what we need as modelers in a milling machine.

Overall, the Micromark I have is a nice machine and it comes a little more "smoothed out" than many of the other rebrandings of the Seig X2 (which is what it really is).  Particularly, it has metal gears in the spindle drive (because the stock plastic ones are prone to breaking), and it is all cleaned up with only a thin film of oil on the surfaces, as opposed to some versions of it that are loaded with a red "goo".

Once I got the jibs snugged up and the head and table checked and set for true with a dial indicator, it is a pretty darn dead straight machine.  It's hard to fault something that can mill within a thou or two for 600 bucks.

But I have two primary complaints:

1. The Z axis travel is a pain.  There is a torsion spring in the head to support all the weight so it doesn't come crashing down if you let it go.   They make air piston upgrades for it, but I really don't mind the spring.
My complaint is that the Z axis rides up and down on a rack-and-pinion mechanism that is too coarse.  So even in super fine adjust mode, it will sometimes hang up on the teeth and then drop by .050".  To avoid this, I have to make sure I keep firm downward hand pressure on it as I adjust it down.  But that's a real pain if you are trying to do any plunge milling or are using it as a drill press.

2. The spindle speed: As narrowminded points out, for the tiny cutters we would like to use, you really want high speeds.  10,000 rpm is good, 20,000 is better.  Most of these Seig X2 mills can only do 2500, and with an optional upgrade, about 4600.   I will say, however, that I'm able to cut with 1/32" cutters pretty well if I'm careful.
Anything smaller than that, however, forget it.  I've tried 1/64" a few times and it's quite hopeless.  They
will just break too frequently to be usable.

[narrowminded]

That's the point Max as your experience suggests.   For what it's worth, I haven't broken a cutter yet and while I pay attention to what I'm doing when feeding and such, it doesn't require any anxiety or puckering of any body parts to accomplish that and the finish remains decent.  And if you get a little aggressive with the feed, the cutter sound tells you that and before it reaches the breaking point.  John has a machine with a speed range of 5,000 to 20,000 RPM so with a dial of the knob he can demonstrate to himself the effect that speed has on the cutting action with these small cutters.  Then envision the slowest setting he has is already twice that of the R-8 machines and the demonstration becomes even more dramatic.  And these things (as most things mechanical) aren't magic.  They are basic metal removal principles that apply any time a cutter meets metal.  Drill, mill, or lathe, it's what it takes to optimize metal removal.  Does that mean you CAN'T coax something less than optimum through?  Not at all and within a window, it works both ways.  Understanding your needs and the principles affords the best opportunity for success, both ways.  And without analyzing or even understanding any of this, a dial of the speed knob can put this small cutter issue to bed, confirming what the principles tell us is true.

[PaulP]

I am also a fan of Sherline. They are very well made machines. They are great for us hobby guys and not to be compared to R8 machines.
Keep in mind getting the machines is only half of it, tooling is the other half. I have spent a lot of time making my own tooling. Acquiring cutters is never ending!
Just got two axis DRO on the mill and that makes machining much more enjoyable.
Paul

[peteski]

Nice setup Paul!

I agree that it is not just the machine but all the attachments and accessories which make Sherline a great tool!  Sherline also keeps coming out with more and more innovative accessories.  The great local English-speaking tech support and easy ordering are also a great perk.  Micro-Mark used to carry Sherline (that is when I bought my lathe back in the '80s). It is too bad they went with the larger (and bulkier) Chinese tools.  I have the Sherline's version of the DRO and I switch it between the lathe and the mill (depending which one I'm using).

[narrowminded]

The Sherline is a more rigid machine, I'm sure, and may have some benefits, fit nicely, between a Proxxon and a Chinese R-8.  The weakest point of the Proxxon is the table rigidity but as mentioned, with the smaller cutters and a careful gib adjustment it's tolerable and because it will never have a large cutter mounted.  And then there's the size, weight and storage as well as price for someone with limited space and only doing the occasional small hobby job.  That was my need.  But with the Sherline or any of the bigger machines there's still the inadequate spindle speed for tiny cutters.  UNLESS... check this out.  It could be a HUGE improvement on a Sherline mill, CNC or manual.  I'd be doing this or something like it utilizing a high speed spindle without question.  There are other spindle types available but the Proxxon has an attractive price for a unit with the speed and a decently true running steel collet rig.  It also can serve as a hand held Dremel type tool, just much smoother and truer running tools.

[jdcolombo]

If I ever decide I need something larger, the Sherline would be my choice.  And if I do a lathe, the Sherline will be the one.  For now, the Proxxon does exactly what I needed a mill to do - easily mill N-scale diesel frames for decoders, wiring and speakers, using a 1/8" double-flute end mill.  Space was also a big consideration - I just don't have a lot of it, and the Proxxon doesn't take up much.  If I had a room to set things up like Paul, I might have made a different choice.

The Proxxon also has the advantage of being able to mount a 1/4" Dremel sanding drum, which I can use to thin the inside of shells (at least until ESU releases it's long-rumored "drop in" board).   I've practiced on the shell thinning - it's still a bit nerve wracking, and I destroyed two old shells by mistakenly turning the adjustment wheels on the X and Z axes the wrong way (- something I've since overcome!), but I've now more or less mastered the technique and it's a whole lot easier than trying to do it with the shell in one hand and a Dremel in the other!

I timed myself doing an older (non-DCC ready) GP7 frame from Atlas.  I needed to mill down the front of the frame for the speaker, cut a center channel for wires, and mill the back of the frame flat for the decoder.  This used to take me about 90 minutes doing it by hand with a Dremel and a combination of cutoff wheel and carbide cutter, and the end result was not very pretty (functional, but . . . ick from the aesthetics standpoint . . .).   With the mill, it takes me about 30 minutes, including mounting the frame in the vise, doing the cuts, and cleaning up afterward.  And the end result looks like it came from the factory.  Really happy with what I've got for what I'm doing.

John C.

PS - I got the Proxxon mills when I ordered the machine, and then ordered some additional ones from McMaster-Carr that are coated.  The M-C mills provide a much nicer finish on their cuts than the Proxxon ones did.  If anyone else goes down the Proxxon route, I'd recommend bypassing the Proxxon mills and getting a set of nice coated double-flute end mills from a machine tool supplier.  They will be more expensive, but you get what you pay for.

[bbussey]

@mmagliaro Max, I'm guessing that you encounter bit breakage on the smaller bits due to manual manipulation of the mill? Since I run my Sherline as a CNC, that isn't an issue as I adjust the feed rate accordingly based on the bit diameter and the spindle RPM. I've gone as small as .005" diameter and not broken any bits (other than through mistakes or stupidity), but the cutting depth is only .001" and the feed rate is incredibly slow (1.0 or less). I don't remember offhand but there is a formula calculation based on spindle RPM, bit diameter, number of flutes, and material hardness. Takes forever to do the cut but it does work.

[mmagliaro]

@mmagliaro Max, I'm guessing that you encounter bit breakage on the smaller bits due to manual manipulation of the mill? Since I run my Sherline as a CNC, that isn't an issue as I adjust the feed rate accordingly based on the bit diameter and the spindle RPM. I've gone as small as .005" diameter and not broken any bits (other than through mistakes or stupidity), but the cutting depth is only .001" and the feed rate is incredibly slow (1.0 or less). I don't remember offhand but there is a formula calculation based on spindle RPM, bit diameter, number of flutes, and material hardness. Takes forever to do the cut but it does work.

Yes, yes, and yes.  I do all manual feed, no CNC.  And with ultra small bits and low spindle speeds, that is a recipe for bit breakage.  There are lots of online calculators that can compute the limits on cut depth, spindle speed, material, cutter diameter, number of flutes and so on.  They are all basically computing how many surface feet per minute the cutter will be trying to cut through a given material, and then they tell you what spindle speed and feed rate you should use.

The problem is, for a cutter like 1/64", even in relatively soft aluminum or brass, the recommended spindle speeds are always 10,000 or higher than that, even for very small cut depth.  And when the feed rate has to be ultra slow (like you suggest 1.0 or less, which I assume is 1" per minute?), it is very very hard to do that by hand.

I've gotten good enough to reliably do it with a 1/32" cutter.
With a 1/64" cutter, I can cut for a bit, but I always end up breaking the bit within a minute or two.  I supposed with a lot of practice, I will get to where I can operate those handwheels smoothly and uniformly enough to manage a 1/64" bit.

But good cutters that small are pricey.

[Sokramiketes]

Yes, yes, and yes.  I do all manual feed, no CNC.  And with ultra small bits and low spindle speeds, that is a recipe for bit breakage.  There are lots of online calculators that can compute the limits on cut depth, spindle speed, material, cutter diameter, number of flutes and so on.  They are all basically computing how many surface feet per minute the cutter will be trying to cut through a given material, and then they tell you what spindle speed and feed rate you should use.

The problem is, for a cutter like 1/64", even in relatively soft aluminum or brass, the recommended spindle speeds are always 10,000 or higher than that, even for very small cut depth.  And when the feed rate has to be ultra slow (like you suggest 1.0 or less, which I assume is 1" per minute?), it is very very hard to do that by hand.

I've gotten good enough to reliably do it with a 1/32" cutter.
With a 1/64" cutter, I can cut for a bit, but I always end up breaking the bit within a minute or two.  I supposed with a lot of practice, I will get to where I can operate those handwheels smoothly and uniformly enough to manage a 1/64" bit.

But good cutters that small are pricey.

I forget, are you using a Sherline?  They have a 10,000 RPM spindle available. 

[Cajonpassfan]

  Wow! That's just too pretty!
Otto K.

[kondor]

When I was looking for a mill I looked at Sieg, Sherline, and Taig.  I do mostly metal working on my mill and lathes.  My Taig mill has been converted to CNC.

I ended up going with Taig.  The main reasons were the leadscrews and gibs.  The larger leadscrews and their manufacturing process gave me greater confidence in their repeatability, however I'm sure Sherline's performance will be more than adequate for most needs.  The gibs on the Taig seemed well thought out and maybe more robust than the Sherline.  I'd stay away from the Sieg mill and lathe.  I own a Micro-Mark lathe and a Taig lathe.  For what I do the Taig is much more enjoyable and less frustrating.  I imagine that's the case with the mills as well.

Two important things that probably weigh more than my comments above:
1. The machine is only part of it.  Tooling is the other half, so budget accordingly.  Don't go out and get ALL the tooling or tooling packages.  Do some research for what fits your needs and buy accordingly.
2. Community.  If your go-to forum for support is here, then get a Sherline since I'm the only person who even mentioned Taig.

Regarding double sided tape:
I usually bolt a sacrificial piece of MDF to the bed and tape stuff down with this stuff:
http://www.mcmaster.com/#masking-tape/=71lj49cpikiuguyvzy

-steve

[mmagliaro]

I forget, are you using a Sherline?  They have a 10,000 RPM spindle available.

No, I'm using the Micromark mill (the Seig X2) with an MT3 spindle (not the more common R8 they use now)
There is a belt drive upgrade kit for it that will get the spindle speed up to about 4600.  But I'm at 2500 maximum right now.

[Ike the BN Freak]

I just need someone who can mill the sides of a few Kato cars for me so I can use them as core kits for brass car sides.  But I gotta figure out when/how many cars I'd want this done with.

[narrowminded]

No, I'm using the Micromark mill (the Seig X2) with an MT3 spindle (not the more common R8 they use now)
There is a belt drive upgrade kit for it that will get the spindle speed up to about 4600.  But I'm at 2500 maximum right now.

You'd be a perfect candidate for mounting a high speed motor off the side of your mill head.  Best of both worlds.  A pretty simple bracket and something as simple as a Proxxon motor.  There are other more expensive options, maybe slightly better but I'd try that one.  No wasted money if you don't like it as it's another Dremel tool and we all know you can't have too many of those.   They don't use a threaded connection at the nose like Dremel but a 20mm diameter machined nose.   A bore and pinch clamp is all that's needed.  Use it on your 1/8" and down milling needs.  It can also be used as a typical Dremel but at a little higher quality, especially the spindle and collets that are steel and truer running than the typical hand tool.  Check that link in my previous post.  There's a reason folks do these things.   And if you searched Ebay and such, I wouldn't be surprised if someone makes a bracket that you could just buy.

[peteski]

The Sherline high-speed kit is just 2 pulleys and a belt.  I wonder if something similar can be made for Max's mill? The motor pulley needs to be larger and spindle pulley smaller. With small bits and high rpms the torque needed will be minimal (something the original motor should handle).

Sherline also warns about the spindle bearings getting hot during high speed operation (because of the preloaded spindle bearings). They give a procedure to decrease the preload slightly to reduce the friction.