My old mill drill needs some work

[Susquatch]

Back when I was looking for a good knee mill, I posted a few things about my old mill drill.

It's a bench top round post model with no real z axis other than the quill. The head can be cranked up and down a fair bit to gain working space but totally loses x&y in the process so fairly useless for in-process milling.

I've actually done a fair bit of work with it over the years and it came with some pretty cool MT3 tooling that I will probably sell in order to get R8 equivalents. It has a crude but very functional power x feed, and a really nice 8.5x36 table with odd-ball 1/2" slots for 1/2" nuts and Bolts. No, that's not a brain fart. Normally, you would see 5/8 slots with 1/2" Bolts. This one really is half and half!

As discussed during my mill search, it's biggest problem is the flaky x/y axis graduations on the leade screws. The crank wheels have 22 graduations on them marked as 0 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, then starting over at 0. Yes, you read that correctly. There really is both a 10 and a zero. As a result, each turn of the crank is 110 thou, not 100.



It's not exactly 110 though, I believe it's actually 111.111111. And in truth, using a dial indicator on the table, the numbers do grow by just over a thou per revolution.

In the previous thread on finding a decent mill, forum members speculated that the mill might have been metric once upon a time. But I don't think so.

I measured the two lead screws very carefully. They are both regular 60° threads on a 7/8 rod. And it just so happens that the normal course thread for a 7/8 bolt is 9 tpi. And 9tpi is exactly.. 0.1111... pitch between threads.

So that mystery is solved. The leade screws are 7/8-9 regular 60° thread and they are probably just plain old ready rod.

In order to sell the mill drill with some integrity, I feel like I pretty much have to replace the leade screws with proper ACME screws in SAE 10tpi or 2mm Metric. If I can't find the right combo of screws and nuts, I'll make them. It's either that or outright give it away.

If anyone has any advice on how to go about all the above, or things you don't agree with, I'd love to hear about it.

The other thing is a proper ID on the mill/drill (make, model, etc) or even where to find that info. That would be much appreciated. Here are some photos.

Anybody recognize the old girl? Or even her bones.

 

[PeterT]

Many opt to install an Asian DRO system which are getting very cheap these days & solve most of these problems simultaneously: odd duck pitch threads and/or dials, backlash discrepancies, table lock secondary movement, mental math errors turning dials, resetting collars, inch/metric conversion, bolt hole patterns, center finding.... etc. Whether the machine & your time & expense are worth it, is really up to you. This assumes your leadscrew is in good shape of course, just odd.

I wouldn't suggest necessarily buying from this site but they have lots of sample installation pics
https://www.dropros.com/

 

[Susquatch]

Many opt to install an Asian DRO system which are getting very cheap these days & solve most of these problems simultaneously: odd duck pitch threads and/or dials, backlash discrepancies, table lock secondary movement, mental math errors turning dials, resetting collars, inch/metric conversion, bolt hole patterns, center finding.... etc. Whether the machine & your time & expense are worth it, is really up to you. This assumes your leadscrew is in good shape of course, just odd.

I wouldn't suggest necessarily buying from this site but they have lots of sample installation pics
https://www.dropros.com/

I hadnt seen that site before. Lots of good info there.

I have thought about installing an x/y DRO system. If I keep it and use it as drill press, I might do that. I have an old Beaver floor stand drill press I might sell instead.

The problem is that my mill drill is prolly only worth 200 as is and maybe 400 with new leade screws. I suppose someone might pay more for it with a set of DROs but I'm guessing that would turn into a bit of a sales job and I'm simply far too honest to be a decent salesman.

Obviously, I could be wrong about all that but my observation is that DROs seem to come free with the used machine if they have them.

If I were to keep it, I'd prolly just do that and be done with it though. The backlash and gibbs on the mill/drill are in pretty good shape but there are no axis locks on it as is. I could turn one of the Gibb screws on each axis into a T-Handle style lock though.

So I dunno, it doesn't seem like that's an economical way to go.

 

[Janger]

It’s worth more than that! I would not be too concerned about the gradations. I agree with Pete a DRO would solve that and not cost too much. There are igaging ones that might run $100ish . Look on busybee.

what does the forum think the mill might be worth? $500 or $1000 I might think?

 

[YYCHM]

Power feeds alone run $200 and that style of power feed even more.

@Susquatch what size is the motor?

 

[phaxtris]

id put a dro on that baby and call it a day, pretty cheap on ali express

 

[DPittman]

It’s worth more than that! I would not be too concerned about the gradations. I agree with Pete a DRO would solve that and not cost too much. There are igaging ones that might run $100ish . Look on busybee.

what does the forum think the mill might be worth? $500 or $1000 I might think?

I'd pay $500 for something like that easy but I think the real market would pay double that without too much difficulty. I've seen much worse advertised the last couple of years for quite a bit more than that.

 

[trlvn]

I see "S" and "F" on the motor...is it 2-speed? Do you know if it is original to the machine?

I've never seen this design before. It is sort of like an RF-30 but not really. Motor mounted above the top pulley. Only 4 belt speeds, right? Different quill lock and fine feed. Appear to be metal handles whereas all the Asian machines I've seen have plastic. Did it used to have a magnetic starter?

Do you know how old the machine is? Is it a predecessor to the RF-30?

Craig

 

[Susquatch]

@YYCHM - I don't know what size motor it is. Definitely sub 1hp. Maybe 1/4? There is no data plate. Best I could do is measure amps but the results of that measurement are very load dependant so I'm not sure it's warranted.

@phaxtris - I want to look into DROs for my two bigger mills Bridgeport Varidrive and Hartford Bridgeport pulley drive Clone. I will look at DROs for all three mills and maybe my lathe too. But I'm not holding my breath at that being affordable or even wise for the mill drill.

@DPittman - I believe I paid 300 for it 8 years ago. So 500 would be awesome. Prolly a fair price too given that I made a new sector gear for the head vertical and repaired the crank handle that both work great now.

@trlvn - You are correct, it's a two speed (non-reversing) 110V motor. I do not believe it's original though since all the electrical is residential stuff. Technically, there are more than four speeds because there are two belts on it and one can be moved without moving the other. I've never moved them though because it's a total PIA. The two speed motor has met all my needs. The table is clearly marked 1982. Seems about right for what is there. I don't know if it was ever capacitor start. There is nothing there now.

I took a few more photos. Maybe they will help.

 

[Susquatch]

It’s worth more than that! I would not be too concerned about the gradations. I agree with Pete a DRO would solve that and not cost too much. There are igaging ones that might run $100ish . Look on busybee.

what does the forum think the mill might be worth? $500 or $1000 I might think?

24" IGaging DRO for $70..... Seems WAY TOO GOOD to be true.......

Ya, each axis has its own readout, but big deal. They could always be stacked on a common display board.

But seriously, $70 in Canada? It is REALLY hard to believe.

But if they work, at that price, you are correct - it seems like a no brainer to me too. Looks like they even have an install kit of sorts.

 

[YYCHM]

24" IGaging DRO for $70..... Seems WAY TOO GOOD to be true.......

Ya, each axis has its own readout, but big deal. They could always be stacked on a common display board.

But seriously, $70 in Canada? It is REALLY hard to believe.

But if they work, at that price, you are correct - it seems like a no brainer to me too. Looks like they even have an install kit of sorts.

You can probable get a 2 axis full function DRO with scales for $200 on AliExpress. Then you get all the DRO functionality (center function, bolt patterns etc). I had IGaging DROs on my lathe that I had to remove in order to make my follower rest. I have no desire to re-install them. Ya, they work but not great, IMHO, battery powered to boot, 2 batteries per display no less.

HXX DRO Set 3 Axis Magnetic Linear Scale Encoder With Digital Readout Digital Readout Display For Mill Lathe Machine|Level Measuring Instruments| - AliExpress

Jeepers..... where the heck was that deal hiding when I was looking for one.

 

[PeterT]

Not taking anything away from the uniqueness of the machine, its similar to other knee-less round post mills in that whenever you raise or lower the head, you have likely gone off course relative to the preceding XY position on the work. Lots of fixes have been proposed & executed on similar RF style mills, usually involving some outboard stabilizing arms. So having a DRO with 0.0001" readout doesn't really solve that particular issue if the head is wandering (I really don't know +/- 0.050" ?). I guess as long as the head position was locked & all the Z movement was confined to quill displacement it might still be worthwhile. I find that's rarely the case, tool stickout distance varies so much just swapping ordinary tools.

 

[Susquatch]

I hear you @PeterT. Frankly, I think you are GROSSLY underestimating the x/y movement (Esp x). I'd guess more like an inch or two....... Its not designed for that. Once you crank it to whatever working Height you want, you lock it down with two HUGE Bolts (see right side photo above with special bolt tool attached), and then it doesn't move. All working Height changes are then made with the quill and fine tuned with the quill wheel. The two quill movement methods are interlocked. It's one or the other, not both.

In my experience, once the head is locked, it never moves. So the x/y/z work just fine thereafter. That said, the rigidity is pretty poor so you would never take heavy cuts anyway.

Tool swaps seem to be fine for me unless they are major. You can't go from a big mill to a little one or from the drill chuck to anything else. That's probably what you meant though. I'm gunna take a look at the DRO that @YYCHM suggested above. Who knows!

 

[Susquatch]

You can probable get a 2 axis full function DRO with scales for $200 on AliExpress. Then you get all the DRO functionality (center function, bolt patterns etc). I had IGaging DROs on my lathe that I had to remove in order to make my follower rest. I have no desire to re-install them. Ya, they work but not great, IMHO, battery powered to boot, 2 batteries per display no less.

HXX DRO Set 3 Axis Magnetic Linear Scale Encoder With Digital Readout Digital Readout Display For Mill Lathe Machine|Level Measuring Instruments| - AliExpress

Jeepers..... where they heck was that deal hiding when I was looking for one.

I'd actually like to jump on that deal for my mills, my lathe, and my mill/drill. But I can't find specifications like working length and precision. The display only shows thousandths yet its called high precision.

I do use tenths on my lathe but probably wouldn't on my mill. Still, with digital systems, you need to be able to see tenths to know which thousandth you are working with - otherwise, it could be rounding up or down and you have no idea which.

It's a great deal price wise, but not so great if it doesn't fit or work properly.

Am I missing something?

Ps - "Jeepers". Brings back memories of the home farm in Saskatchewan. All the ladies used that word instead of the ones the guys used....... Nobody says Jeepers out east here.

 

[YYCHM]

I'd actually like to jump on that deal for my mills, my lathe, and my mill/drill. But I can't find specifications like working length and precision. The display only shows thousandths yet its called high precision.

I do use tenths on my lathe but probably wouldn't on my mill. Still, with digital systems, you need to be able to see tenths to know which thousandth you are working with - otherwise, it could be rounding up or down and you have no idea which.

It's a great deal price wise, but not so great if it doesn't fit or work properly.

Am I missing something?

Ps - "Jeepers". Brings back memories of the home farm in Saskatchewan. All the ladies used that word instead of the ones the guys used....... Nobody says Jeepers out east here.

The IGaging DROs only display to x.xxx. My mill DRO displays to x.xxxx and I hate that last digit. It's always fluttering around due to vibration. Locking the table or quill shifts it. I don't find that last digit particularly useful at all.

A 3000 lb Bridgeport might not have that issue but you drill/mill will. The scales for the AliExpress unit are 5 Micron. Sometimes the precision on the DRO display is programable, I wish mine was.

 

[Susquatch]

The IGaging DROs only display to x.xxx. My mill DRO displays to x.xxxx and I hate it. The last digit is always fluttering around due to vibration. Locking the table or quill shifts it. I don't find that last digit particularly useful at all.

Sorry, I think you misunderstood me. I don't find the tenths all that useful either. But I do find thousandths useful. The problem with digital readouts is that they show thousandths, but you don't really know if that has been rounded up or down. So even though they show thousandths, it's really +/- 2 thou. Even though the tenths is jumping around, it at least tells which thou it actually is.

Maybe look at it this way. With an analog 0.001 DTI, you do the rounding yourself by looking at which line the indicator pointer is closest to and you know if it's above or below.

With digital, you are at the mercy of the programmer who might be rounding, averaging, or truncating.

So, all that said, do you think the readouts on those DROs might be metric?

 

[YYCHM]

So, all that said, do you think the readouts on those DROs might be metric?

Inch/mm is programable at the push of a button, so you're probably right about the image only showing 3 digits due to it being in mm mode.

 

[phaxtris]

the cheap dro i have from ali-express shows 4 decimal places, thats ten thousandths...so you could round either way you wanted and still be just as accurate as a thousandths dial gauge

myne changes from metric to imperial with a push of a button, although i would suppose the scales are most likely metric and there is a conversion going to an imperial display

when i ordered myne the seller messaged me for the lengths of the scales i needed, and sent the appropriate ones, any wrong length was my own fault

as for the fitment....thats on you to figure out, i think most dro's are that way

 

[Susquatch]

the cheap dro i have from ali-express shows 4 decimal places, thats ten thousandths...so you could round either way you wanted and still be just as accurate as a thousandths dial gauge

myne changes from metric to imperial with a push of a button, although i would suppose the scales are most likely metric and there is a conversion going to an imperial display

when i ordered myne the seller messaged me for the lengths of the scales i needed, and sent the appropriate ones, any wrong length was my own fault

as for the fitment....thats on you to figure out, i think most dro's are that way

This was all solid gold! Thank you @phaxtris! That explains why I can't choose the length!

I doubt the basic info is metric or SAE. It's probably just a digital count of some kind with no units at all. I'd bet that it is most likely a count of accumulated events of some kind. That's how most digital systems work. For display purposes, the program in the DRO control box converts that digital quantity into metric or SAE distances according to the status of the metric/SAE switch.

That's what I was getting at earlier when I said that the device programmer decides how to calculate the display. Programmers are seldom engineers and even more rarely machinists. And that's where the problems begin.

But hey, this coming week, I'll measure my machines and then order a few systems!

Thank you again!

 

[phaxtris]

You are welcome

I don't mean to argue but I believe you are mistaken about imperial/metric scales. Most of the Asian dro's I have seen have a 5 micron resolution, the glass scales inside the linear encoder (scale) need to have graduations at a specific distance to be of any use, given the resolution of being exactly 5 microns and not some round imperial measurement would lead me to believe fhe scales are graduated in metric....making the scales effectively metric