Where to get good used mill

[RobinHood]

It's probably an early offshore unit because both spool markings on the table have 110 graduations per turn (yup a royal pain)

I have heard about these oddball dials before - especially on older off shore machines.

Here is my best guess as to how they arrive at 110 divisions: the lead screw they used is likely metric. Something like a TR40x14(P7)LH. What that means is the nominal OD of the trapezoidal thread is 40mm. (Probably not that big of an OD, but you get the idea). It has a lead of 14mm per revolution, with a thread pitch of 7mm. That means it is a two start screw (14/7=2).

How does that give us 110 divisions on the dial? Well, 14mm is about 13.97mm. 13.97mm = 0.55” per turn. 0.55” / 110 = 0.005” for each division —> as is stamped on your dial. Hence the odd ball number of graduations.

 

[Brent H]

@Susquatch : https://www.kijiji.ca/v-power-tool/...p_ios&utm_medium=social&utm_source=ios_social
$2750 - no views yet except me

 

[Dabbler]

THait is a great machine in good condition.. The motor swap will cost about 400$ but it is worth it -UNLESS there is a hidden serious defect.

 

[Susquatch]

The table is very similar to RF30. Same as main casting of the bottom part. The top obviously is not RF30. I wonder whatever the mill head is from the same machine or different machine. Or maybe you have some limited edition of a machine

I do not know, nor even an inkling. The gray paint on all the parts is thick and multi-layered - been there a long time.

Although the bed might look similar, there is those base-11 crank handles. Hard to imagine those being done as part of any upgrade or refurbishment. I believe they are original.

However, I am almost certain that the original motor has been swapped out to a 2 speed 110V motor. The adapter plates do not look remotely OEM and the switches and wiring all look residential.

 

[Susquatch]

@Susquatch : https://www.kijiji.ca/v-power-tool/...p_ios&utm_medium=social&utm_source=ios_social
$2750 - no views yet except me

Windsor is only an hour from me.

I have seen and like First Mills. But the timing sucks. Unfortunately, I have a badly sprained ankle and grandkids coming over tomorrow. So I sent him a note to see if he would take a deposit to hold it for me till Monday assuming he would vouch for the condition, wear, bearings, ways, and slop.....

I didn't try to haggle.

 

[Susquatch]

I have heard about these oddball dials before - especially on older off shore machines.

Here is my best guess as to how they arrive at 110 divisions: the lead screw they used is likely metric. Something like a TR40x14(P7)LH. What that means is the nominal OD of the trapezoidal thread is 40mm. (Probably not that big of an OD, but you get the idea). It has a lead of 14mm per revolution, with a thread pitch of 7mm. That means it is a two start screw (14/7=2).

How does that give us 110 divisions on the dial? Well, 14mm is about 13.97mm. 13.97mm = 0.55” per turn. 0.55” / 110 = 0.005” for each division —> as is stamped on your dial. Hence the odd ball number of graduations.

This is great info! Best of all, it makes sense!

Why the idiots would have done that though is beyond me! Who can't convert between metric and SAE these days? They should have just left it alone.

As I indicated earlier, I believe it was built that way at the factory.

I will take a much closer look at it, armed with your info, and see what it takes to convert it back to metric. With some luck, it might be as simple as turning down the back half of the graduation drums to remove the existing marks and then remarking it properly. Wouldn't that be wonderful! It would make the machine more useful to me for as long as I have it and easier to sell too!

Thank you!

 

[YYCHM]

Wouldn't that be wonderful! It would make the machine more useful to me for as long as I have it and easier to sell too!

A DRO would resolve your issues. Never have use the dials again and switchable between Imperial and Metric.

 

[Brent H]

@Susquatch : hopefully the seller is a good dude and you are good to go. The first mills are near copies of Bridgeport’s as you can get so parts should be interchangeable for the most part.

Good Luck and hope that ankle gets better quick so you can chase around those kids!!

 

[Dabbler]

My 'First' mill is a bridgeport in almost every aspect, except their castings are much thicker, and the base is wider by 3" all around

 

[Susquatch]

THait is a great machine in good condition.. The motor swap will cost about 400$ but it is worth it -UNLESS there is a hidden serious defect.

In my mind, play in the Gibbs, slop in the frequently used section, Quill bearing play, rough or badly worn gear play, and broken parts are the main concerns to look for.

But I've never used (let alone owned) a mill this size. Is there anything else I should be looking for before I buy?

 

[Susquatch]

@Susquatch : hopefully the seller is a good dude and you are good to go. The first mills are near copies of Bridgeport’s as you can get so parts should be interchangeable for the most part.

Good Luck and hope that ankle gets better quick so you can chase around those kids!!

He has not committed to a deposit nor turned it down, and he hasn't attested to its condition yet either. But he did say that he was available so I could look at it any night after 5 next week. I have no idea how to read that.

I guess we will see next week unless it's gone before then.

 

[Susquatch]

A DRO would resolve your issues. Never have use the dials again and switchable between Imperial or Metric.

I've looked at getting a pair of DROs but it just didn't make sense to throw that kind of money at a mill that I'm not happy with in other ways. It just seems wiser to buy a better mill and add DROs to it if it doesn't have them already.

Maybe I'm not looking at it properly, but that's been my thinking to this point.

 

[Dabbler]

I'd go out of my way to try it out before a committed adversary buys it out from you. If you don't like it, no harm done. Key things to check: flaking on all of the ways ESP the Y ways/ Backlash in X and Y. Have him show you the power downfeed works. Check for slop in the spindle bearings. Take out the drawbar and see if it is badly galled/damaged/stretched in the threads.

Listen to the spindle turning under power at about 600-800RPM. ther shouldn't be much noise - no clunking or bearing rattle

[edit] and backlash on the X axis (and Y but that's usually okay) 70 thou and greater is trouble - not a red flag, but it would affect the price
that's about it.

 

[Brent H]

@Susquatch : I would read that if the guy is available any night after 5 next week then set an appointment to see him Monday at 5:05 or his earliest best convenience. if you are first to see it live you can be the first for anything after that.....

 

[Susquatch]

......... How does that give us 110 divisions on the dial? Well, 14mm is about 13.97mm. 13.97mm = 0.55” per turn. 0.55” / 110 = 0.005” for each division —> as is stamped on your dial. Hence the odd ball number of graduations.

In the process of thinking about converting my mill back to metric, I arrived at another (probably dumb) question.

Why would one turn of the crank be designed to be 14mm? That almost seems as weird as 55 thou. Wouldn't it have been better to design it to be 10mm, or perhaps even 20mm? It just seems totally silly to have to use a calculator to determine how many turns it takes to get to some target dimension. It also makes fast cranking totally impractical.

 

[Susquatch]

I'd go out of my way to try it out before a committed adversary buys it out from you. If you don't like it, no harm done. Key things to check: flaking on all of the ways ESP the Y ways/ Backlash in X and Y. Have him show you the power downfeed works. Check for slop in the spindle bearings. Take out the drawbar and see if it is badly galled/damaged/stretched in the threads.

Listen to the spindle turning under power at about 600-800RPM. ther shouldn't be much noise - no clunking or bearing rattle

[edit] and backlash on the X axis (and Y but that's usually okay) 70 thou and greater is trouble - not a red flag, but it would affect the price
that's about it.

All excellent advice and much appreciated.

One question though..... 70 thou backlash seems like a very high level of backlash to me. If one turn is 100 thou, 70 would be more than the thickness of a tooth on the lead screw. Did you perhaps mean to say 7.0 thou?

 

[Brent H]

@Susquatch : he would be meaning 0.070" - one thing with the mills is that some backlash can be adjusted out with the lead screw nuts. if the mill is in decent shape you can adjust this down to say 0.010" to 0.015" and the screws will be only slightly tighten as you get out to the end of travel and will slightly loosen as you move the mill through the middle zone. A new mill adjustment is typically 0.005" backlash so 15 to 25 thou is not crazy bad in the higher worked zones. It all depends on what your plans are.......

 

[Susquatch]

@Susquatch : he would be meaning 0.070" - one thing with the mills is that some backlash can be adjusted out with the lead screw nuts. if the mill is in decent shape you can adjust this down to say 0.010" to 0.015" and the screws will be only slightly tighten as you get out to the end of travel and will slightly loosen as you move the mill through the middle zone. A new mill adjustment is typically 0.005" backlash so 15 to 25 thou is not crazy bad in the higher worked zones. It all depends on what your plans are.......

Your latter numbers make sense to me. 005 sounds about right for a new machine tweaked to the 9s. 15 to 25 also sounds possible. Even 25 makes some sense for a heavily used machine. And I get how the nut can be split and adjusted to reduce backlash.

But I can't see how you get to 70 thou. Of course, I assume that a typical lead screw has a 10 tpi single thread pitch. So the tooth thickness is about 50 thou. To get to 70 the entire tooth would have to be gone. Of course, that assumes that a typical bed crank has 100 thou per turn - which may or may not be true. If one turn was 200 thou, then 70 is possible but still wow.....

Anyway, I guess it doesn't matter. I will see what the graduations are when I get there and look at it. I can always do a calculation of reasonable freeplay and wear then.

 

[Dabbler]

@Susquatch Unless it has ball lead screws, expect even .010 from the factory. In a well built machine the primary wear will be on the bronze nut, all things considered. Even lightly used machines will have up to .020 backlash. Once the backlash gets to .050 or .055, the nut is worn to a sharp point, and wear will increase dramatically.

None of this is a deal breaker - you can buy a new nut from HW machine repair for a couple hundred, or you can make your own. If I run into an old machine that has .005 backlash, then I know that the seller is savvy, and has adjusted the play out of the lead screw. This only happens for a machine where the nut is completely worn out, and it makes you suspect other things he has hidden. it lowers the price a lot, just for the trouble and risk.

If the spindle turns without excessive noise, all lead screws work, and the speed changes smoothly (in a variable speed version) - then the machine is workable, ans the rest is just about price. For a really worn out lead screw, I'd spend perhaps 2K on a large mill, because of the work needed to return it to my standard. You see if the lead screw is worn, it talks to significant hours and/or poor lubrication practices. I expect some of the flaking to be worn through. That's not much of a biggie, because hobby hours are low, and it makes it undesirable for professional use. It also lowers the final bid price.

This all goes to "what is it worth to you"... if you are desperate, or if you have a mill already, that also influences your offer.If I could find a Mikron VF2 in good condition, with affordable transportation (nearby or at a good port of lading) I would be happy to sell ALL my mills to buy it. But that's just me. I know how solid and versatile, accurate and convenient these mills are. But that's just me.

 

[Susquatch]

@Susquatch Unless it has ball lead screws, expect even .010 from the factory. In a well built machine the primary wear will be on the bronze nut, all things considered. Even lightly used machines will have up to .020 backlash. Once the backlash gets to .050 or .055, the nut is worn to a sharp point, and wear will increase dramatically.

None of this is a deal breaker.....

....... If I could find a Mikron VF2 in good condition, with affordable transportation (nearby or at a good port of lading) I would be happy to sell ALL my mills to buy it. But that's just me. I know how solid and versatile, accurate and convenient these mills are. But that's just me.

Thanks for that very thorough explanation. Although I still feel a bit like a 16 Yr old babe in a forest full of wolves, I also feel much better armed to find something decent. Either way, my ripe old age should give me patience - provided I keep reminding myself of that.