Tearing down the smithy! advice on vfd while i'm in there?

[korecoa]

Hey all, after using the smithy for this season and getting some good use out of the lathe I started to mess with the milling operations and i've determined..well, it sucks. Maybe it's not supposed to suck..but it does. I put a dial on my main ways and placed the indicator on the edge of my cross slide and moved it around..a good solid 5 thousands wiggle. This would explain why I couldn't make a straight pass on the milling machine to save my life. So i decided nows a good time for some maintenance, cleaning and wear and tear part repair. I removed the cross slide, and the main carriage slide. I'm going to clean up the gibs of each as well as hit the ways with a stone. I will relube, and while i'm in there i'll replace the cross slide feed screw, cross slide feed nut as well as the main half nut that engaged the power feed. I figure these are wear and tear parts that will cause some tolerance headaches.

So my question is two part. Is there anything else any of you would suggest i inspect/replace while i'm into this machine? Also, i'm dabbling with the idea of putting a vfd and a 1hp motor on this thing to run at 110volts. Does anyone happen to know if a standard 56c motor will fit in the factory motor mount location? I read the factory motor is a little smaller than a regular 56c frame motor but i have not confirmed. Anyone with experience doing a vfd conversion I would love to hear any info you can provide.

Thanks!

 

[wa5cab]

I wouldn't recommend going over about 1/2 HP on 120 VAC single phase. Especially if there are any other loads on that circuit.

 

[markba633csi]

These machines are known for not being fabulous millers, it sounds though like your cross slide gibs need to be readjusted
They should be just snug enough to remove the play while still allowing movement. Also, remember that there will always be a small amount of backlash in the leadscrews and you need to take that into account when setting up your milling jobs
Consider adding a dedicated mill to your tool collection at some point

 

[bill70j]

Is there anything else any of you would suggest i inspect/replace while i'm into this machine?

I have a Smithy 3-IN-1 and just went out and did some checks. My machine is a 2005 Granite Classic 1324, and may be different than yours, but here is what I found, FWIW.

I placed a DI on the ways and positioned the carriage near the lathe spindle where most of the wear is. Then I pulled up, down, and side to side with a fair amount of force, first on the carriage, and then on the table. I saw virtually no movement of either the carriage or the table relative to the bed ways (<0.001"). Neither the carriage nor the table was locked down.

Then I tightened the millhead locking studs as tight as I could get them using the Smithy wrench. I placed the DI on the table and pulled up and down, then back and forth on the mill head and measured 0.004" of total head movement relative to the bed ways in the vertical, and 0.002" in the horizontal. That's a mess.

I run with the carriage and table gibs pretty tight, which may be one reason that I see no movement compared to your experience. But on the millhead (and spindle) movement, I have not yet done the work required to reduce that slop. If you haven't done so, you may consider searching the smithy-machines IO group. There are a number of good suggestions on tightening up the millhead and the mill spindle.

One other thing you might consider is replacing your compound tool post with a solid tool post. You lose the ability to turn a short taper, but it's not a major deal to put the stock compound tool post back on for single point threading and short tapers. I was amazed at the increased rigidity that change made. The horrors of using form tools and parting off have decreased dramatically on my Smithy.

As far as the motor goes, mine is a D/C variable speed spec'd at 1.5HP. I run it on a 20A circuit. I have stalled it occasionally at very low RPM's but other than that, it has served me very well for 15 years.

One last thing. I finally spent the time to level the machine and at the same time secured the bench to the wall studs using angle iron and a laminated 2x4 shelf spanning the distance between the wall and the bench. Then I loaded the shelf with the heaviest tooling I have. That went a long way to reducing movement of the bench and vibration of the machine.

HTH, Bill

 

[Grandpa's Barn]

I have a Midas 1220LTD purchased new early this year. Everything was full of cast iron grit from manufacturing. I disassembled the cross slide and thoroughly cleaned, stoned and carefully adjusted gibs on assembly. Last week I made stepped keys for the Kurt vise to table slots, was able to hold .0002 across 4" traverse, they were light cuts. The power feed makes very smooth cuts but using hand feed it feels as though the screw is bent, I'm thinking of replacing it with a ball screw. This would also speed up the very slowwww... power feed

I'm in the middle of replacing both motors with 1 HP 3PH motors and powering them with VFDs.
This motor will not fit the existing mount but it's smaller than a 56C face and has mounting pads for a base. I've made 2D CAD drawings of the motor and mount if any are interested. I'm also putting one of these on my drill press.