Talk to me about milling machines

kuraki said:
I would think they're all fiber gears.
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That would make more sense...It also seems that they considered it a failure point and someone developed the belt conversion.

The PM-727 is using hardened steel gears which for that price machine makes more sense than plastic gears.
 
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Busto said:
Butch,

How long did it run before the gears went South? Just curious since most of these with the smaller HP I could see have that problem because of trying to run at faster speeds and driving the machine beyond the Gears limits. So there is a conversion to belt drive and sounds like that eliminates the gear noise that's cool:cool:and produces more RPM:cool::thumbsup:....

ETA....Wonder if these clones all have plastic gears???
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lasted a whiel and i wass pushing it way over the limit (including tilting head 45 degrees and using a 1.25 inch ball end mill to make fullers )
 
butcher_block said:
lasted a whiel and i wass pushing it way over the limit (including tilting head 45 degrees and using a 1.25 inch ball end mill to make fullers )
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That's never a happy ending and then waiting on repair parts to complete a job to boot...Well the up side is the belt conversion.
 
Not a lot to add here that's not been covered, but I'll add a video recommendation: Open Source Machine Tools' Youtube channel, the videos Milling Machine Basics I and II with Eric Vaaler of the MIT prototype shop. That's a great series for theory and setups on manual Bridgeport type knee mills, most will apply to what you're getting.
 
Well I got it in and mounted guys! Thanks to everyone who chimed in with advise!

So when researching how to tram the spindle to the x and y axis, I keep seeing a dial test indicator swing arm that can go in a 360° circle. All I picked up was the dial test indicator so I don't have this swing arm. Any recommendations on what to get?

I keep reading about squaring and tramming... Is the only thing I need to worry about tramming the spindle to the x and y axis or do I need to make sure the column is square to the table as well or something else? I read about using a cylindrical column square and running the DTI up and down but don't know if that's needed. Any input welcome!

Edit: will this work?
 
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The thing you linked is an off brand Indicol and is what most people use for tramming as well as other mill indicating activities. Should work just fine, but make sure the size range of the clamp will fit around the nose of your spindle before buying. Most are sized for a bridgeport nose, which should be comparable if your machine is R8.

Tramming is aligning the plane of the spindle arc parallel to the table face. If I'm looking at the mill correctly it has vertical movement in the column and the quill? If the column and the quill are not in line with each other you could end up in a situation where either column movement effectively also moves in a linear fashion, or where quill travel is not perpendicular to the table. (although the latter should be resolved by tramming, unless the spindle bearings are not inline with the quill, which is unlikely and if it were the case, nothing you could do about)
 
kuraki said:
The thing you linked is an off brand Indicol and is what most people use for tramming as well as other mill indicating activities. Should work just fine, but make sure the size range of the clamp will fit around the nose of your spindle before buying. Most are sized for a bridgeport nose, which should be comparable if your machine is R8.

Tramming is aligning the plane of the spindle arc parallel to the table face. If I'm looking at the mill correctly it has vertical movement in the column and the quill? If the column and the quill are not in line with each other you could end up in a situation where either column movement effectively also moves in a linear fashion, or where quill travel is not perpendicular to the table. (although the latter should be resolved by tramming, unless the spindle bearings are not inline with the quill, which is unlikely and if it were the case, nothing you could do about)
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Thanks for chiming in man. Ok I just ordered that one, I'll check to see what I need to do. The machine only has x axis head tilt (no nod feature) but I suppose I could shim if needed.
 
Indicol is the easiest, but you can often easily remove the arm from an indicator stand/holder, and chuck it in a collect, locked at an angle if you don't have one. Or simply bend a bar of round stock that will fit one of your indicator clamps that usually comes with the indicator sets.

A lot of the indicols I've seen have a clamp and will fit a lot of sizes of quills. Find one that works, it's a good investment. Tramming is something you need to do periodically, and is one of the first things you should check when you get unexpected results. It's why I often recommend a square column mill to lots of people. A tilting head is really useful for a few random things that most rarely need, and a huge source of problems the rest of the time, for most.
 
javand said:
Indicol is the easiest, but you can often easily remove the arm from an indicator stand/holder, and chuck it in a collect, locked at an angle if you don't have one. Or simply bend a bar of round stock that will fit one of your indicator clamps that usually comes with the indicator sets.

A lot of the indicols I've seen have a clamp and will fit a lot of sizes of quills. Find one that works, it's a good investment. Tramming is something you need to do periodically, and is one of the first things you should check when you get unexpected results. It's why I often recommend a square column mill to lots of people. A tilting head is really useful for a few random things that most rarely need, and a huge source of problems the rest of the time, for most.
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Awesome thanks for the confirmation of that!!!

Continuing on as I watch videos... do I need to get an edge finder set (something like this) - do you find you use any of these much? I imagine the center finder would be very helpful for holes. Or maybe it's not needed w/ a DRO? Also, should I pick up a coaxial indicator (like this)? Looks super helpful for centering cylindrical objects...
 
You can, the edge finder and coax indicator are definitely things that are convenient, but with the dial test indicator and holder you bought, you can both edge find and find the center of holes or bosses. You can also use an edge finder to find the center of holes.

Edge finder is worth picking up. Coax probably not.
 
Well after a few months from my original reply in here following everyones advice, i held out a bit longer hoping for a deal to pop up on CL, but yeah, it's a lost cause on finding anything old and built to last. As much as i would love an oldie that will outlive me and do far more than i ever would need from it, i can't justify waiting any longer. nearing 2 years hunting, nuff said.

I've settled on these choices as of now.
http://www.precisionmatthews.com/shop/pm-30mv/ (with dro)
http://www.precisionmatthews.com/shop/pm-727m/ (with dro)
https://littlemachineshop.com/products/product_view.php?ProductID=5500&category=1387807683

What would you machinists turned knifemakers suggest out of these choices? And is there anything better bang for buck, or better quality in similar pricing i should be looking at instead? I'm at most using it for knife making tasks, and building knife making tools/fixtures. Nothing too extreme. I don't do engine rebuilds, no plans to do anything super thick or large dimension. Seems like either of these 3 would be good choices, at least from my novice level knowledge on the topic.. All 3 fit my space just fine, and i've already got the spot wired for either 110 or 220 so not a factor for me. Just want to make sure im spending my money wisely on something that isn't going to come up short, or fall apart on me.
 
The PM-30 seems like the better choice for a few dollars more. 2HP @220V much better power over the 1HP of the 727 @115V. The PM-30 has variable speeds from 50-2250 rpm vs the 727 which is a "6-Step" speed control of 115-1750 rpm. They are very equal in most everything else the 30 is a little heavier so mass will help dampen vibration. Overall of the 3 that would be my choice. I have not used a table top mill, but the PM series seem to be popular as a clone of the original Rong Fu Taiwanese made machines(wouldn't be surprised if they were made by Rong Fu painted to importers color selection like Grizzly models) which are pretty well made castings from what I've seen. Best of Luck on your decision!
 
i see you have showing with DRO just making sure you saw that it was quil only dro and really not that big a deal for most knife work. i woudl love a DRO on my X and Y on ether of my mills. i woudl go belt drive for noise issues the more mass will be good on the larger mill tho im not sure why they dont have a tilting head (not a deal braker) the thing i really question on all these smaller mills is why is top RPM so low? small cutters need speed and carbide cutters even more so. my bridge port tops out at like 5200rpm while my mini mill with belt convertions 4300rpm (stock is2500rpm)
 
Yeah quill DRO is mostly useless.


Also, I personally never use an edge finder, there's a million ways to skin this cat, and usually you've got to "make the edge" by cutting it with an end mill unless you're using some specific parts that have been pre-cut and you know they have exact dimensions or something. If you make your edge by cutting it, you know it's half the cutter diameter from the center of the quill, assuming things are as they're supposed to be, and you know you've got an edge that's roughly square (at least to the Y axis).


Most of those edge finders are audible, and the ones I've seen aren't exactly "precision" i.e. they just get you in the ballpark, and you still have to do some calculating. Even if you're not squaring the edge, it's just as easy to mic your cutter, then touch it off on the edge.
 
Those are good points. Since there are indeed often several ways of setting up or running a machining task, at some point it becomes a matter of personal style. I am habituated to the use of an edge finder when setting work up, so I do it pretty often and value it as a part of the process. It's pretty simple to do, more convenient than a typical dial test indicator for basic stuff, but also much more limited in use. I really like a coaxial for centering in holes but certainly it's a second or third tier purchase when tooling up. A dial test indicator and an edge finder are both what I'd consider first tier.
 
So I got it in and set up, thanks for everyone's help - wanted to give an update! Since my shop has a wooden floor I got some white oak kiln dried hardwood and used some lag screws to screw those down into the studs underneath, then ran some lag bolts through them to secure the mill to the floor - worked perfect and much more rigid now.

Got my x axis power feed installed, along w/ the DRO and my Moffatt lamps (w/ flood light LED's) installed.

I checked the run out on the inside of the spindle and it's decent from what I can tell at around .0003" - what do you guys think? Seems tolerable for a benchtop mill. Next thing I have to do is shim under the front part of the column as it's out by a couple thou on the y axis but for now I have some projects I have to knock out first!

Still have to install the Fogbuster - and figure out how to use my rotary table (seriously have to figure that out)!

i-Vwmsb2C-X2.jpg
 
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