What are the most cost-effective modifications to a Grizz or HF mini-mill?

HMF

HMF

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A question to those of you who own mini-mills.
Which are the most cost-effective modifications that you can make to a HF or Grizzly Mini-mill?

DRO? X\Y\Z scales?
Column Stiffener?
Head Counter balance?
Fixing the gibs?
Power feed?
Belt drive?
Install Delrin washers for the Y-axis leadscrew instead of thrust bearings?
CNC?
Tormach quick change tooling?
Belt drive conversion from LMS?
Spindle lock from LMS?
High quality custom bench?
Get all surfaces \ moving parts remachined & add a column support?
Fitting thrust bearings to the spindle?
Air spring?
Bolt mill to a slab of granite?


Let us know what is on your list of TOP modifications!

Best,

Nelson
 
I have the Grizzly version of the SX3 I am new to serious machining and used steel for the first time on the Steve Bednair version of a Ball Cutter which is half done. I can live with most of the compromises in the machine such as No power feed ...etc. and I am very happy with it BUT i sure would love to have X " Y DRO ( it has a Z dro as standard.. But I can't spend 600 for a kit to add Y &X dro.. but it sure would be nice.. a stiffer column would be helpful but it is manageable for me so far. any tips for ACCURATE dro on the cheap???
The unit on the Z axis is really just a digital caliper bolted th the unit.....close to dro ...But no cigar
 
Probably the cheapest and easiest thing I did for a big payoff was to buy a longer rack from LittleMachineShop, one that had no mounting holes, and put that on my column to increase the "Z" travel and capacity. I only used 2 screws to mount it, one top and one bottom, so in typical use the pinion does not go over the weaker drilled areas of the rack when under any load. This gives over an inch more "Z" that is fully usable for machining, plus maybe another inch where the head slide is partly off the dovetail but still legit for changing tools or hopping over obstructions.

But it is almost a flat out requirement, in my opinion, to brace the column up. The stock column mounting arrangement totally a joke... I can't imagine what they were thinking.

As far as what I would not do, I never saw the point of the air spring conversions... the torsion arm on mine works good enough, and allows the extra "Z" travel I added without a problem. Belt drives seem attractive until you see how they increase spindle speeds compared to the stock low gear. I like working in steel, and I need the torque and low speeds. The stock spindle lock seems great to me; lots of mill/drills and even smaller knee mills would die to have a spindle lock as simple and effective and convenient as the mini-mill comes with. And CNC... well it sure seems like a waste of time putting CNC on such a flimsy machine.
 
Allthumbz link=topic=1403.msg7534#msg7534 date=1301000283 said:
Let us know what is on your list of TOP modifications!
Click to expand...
Poor mans modifications¦

Number 1 was wheels and leveling jack screws under the stand.
http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/wheels760.jpg

http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/BlackWheels760.jpg

Number 2 was a handle on the motor plate.
http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/MotorHandel2780.jpg

http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/MotorHandel3780.jpg

Number 3 was adding a oil drip gutter under the screw. Now when I oil the screws I don't get oil all over everything in the cabinet stand, it runs out the back.
http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/OilGutter780.jpg

http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/oilgutter2780.jpg

Number 4 was adding tooling racks to the door on the cabinet stand.
http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/cabnet780.jpg

Then I had to screw down this cover that came off the first time I used it.
http://i131.photobucket.com/albums/p315/96FXD/Drill Mill/Motorhandle.jpg

Next, will be poor mans DRO's

I'm always in search of links with details and thousand word photos of poor mans DRO set-ups.
That could be an entire thread itself.
 
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HF X2, I'm in the process of making a belt conversion, stiffening the column, power feed for the x axis, and will add DRO in the future. Mine ran almost 2 years before the dreaded gear explosion.
 
I can echo what 0369 says. My X2 equivalent went several years and suddenly threw gear parts everywhere. I made up a 2-speed belt conversion using lathe-cut aluminum pulleys and a sewing machine belt. It's SO much quieter. Well worth doing. Don't wait for the explosion.

I added a reversing switch to the motor control. It comes in handy when I want to use power to start a tap. The DC motor control run dead slow will start to cut just enough thread before it kicks out to guide the tap for hand threading. It's nice to have the reverse to back out the tap. Easy to do with a DC motor.

Other than that, all I've done is add a dial indicator to the spindle, and, of course, the metal stand when I had to get rid of the bench it was on to make room for the shaper. The stand still needs a bit of work - a bit shaky.

I have a 25-size mill/drill, but I'm keeping the mini because it's handy to do a quick operation without resetting the 'big' mill.

Mike
 
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Mike if it's at all possible I'd be keen to see pics of your belt drive conversion. I've already replaced one gear I broke in my X2 clone and I looked into the little machine shop belt drive but it's not going to fit mine without some major mods. I plan to make my own conversion at some stage and I'm keen to see what others have done. :)
 
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I'm in the process of getting a new knee mill set-up in my shop, but for years I used a Micro Mark mini mill and did all sorts of things with it. The only modification that I ever made to it was scraping and lapping the gibs. I even built an AR-15 from a forging on it, but I did have to have a friend with a full size mill drill and tap the buffer tube hole.
 
Everyone who has one of these "mill-drills" or buys one (fitted with R8 or other collet system with a draw bar), be sure and check the draw bar out. I had an ENCO in the '90's with R8 collet spindle and the 7/16-20 draw bar. After using the machine for about six months, I tightened a collet holding an end mill. I felt the bolt turn just a "little" bit weird, but I thought (Dah!) that the collet had just pulled up on the taper. After a few passes the collet dropped out of the spindle with no warning and went by me across the shop. I was lucky.

Examination showed that the draw bar was two piece with the hex nut fixed to the bar with a solid (tapered?) pin. The assembly had been blued or surface treated and the ends of the pin were virtually impossible to see without very careful study. The "slip" I felt was the pin beginning to shear. I immediately turned up a solid draw bar on my trusty Logan 10" lathe. Don't let this happen to you, that thing could have really hurt!

I sold the mill-drill in 2000 (Y2K!) and bought a Grizzly knee mill. This is a step up and at that time the price was right. It is a 9 X 42 (I think) and the head will rotate but not swivel. I really like this machine. Needless to say the first thing I did before I pulled up any tooling in the spindle was to check the draw bar - yes, it is one piece. Be safe, Geoff
 
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