King Kc-20vs Milling Machine

[WayneP]

Wayne -
OK, I'm just speculating ... but the specs on the KC-20 state that the spindle is R8. If your larger collets are losing tools, I'd say it was time to buy some better collets.
PS - When tightening the draw bar, is there a way to lock the spindle rotation, so you can tighten things up snugly? If not, you might want to look for or rig up a way to lock the spindle. No need to make it "farmer tight," but pretty snug is good.

Hi Hman

Yes my machine has the R8 spindle too. The collet that was holding my cutter when it slipped was the tormach collet. I don't think the collet is the problem. True, you don't want to overtighten a collet but "a bit tighter" seems to be required and when I try to do that the outer sleeve (the part you put the other wrench on when tightening) loosens off. This sleeve that keeps loosening off is the main reason you can't snug the collet up. At some point I will take it all apart and see what's going on, maybe loctite the thing if possible. I'm sure I can correct it but as I said before I don't often use mills bigger than 1/2" as most of my work is small stuff.

Hbilly

One thing you might want to do is a search on the G0704 and see what all the cnc guys are doing with this machine and the kind of parts they are making. There are home upgrades for power, cnc conversion, it amazing all the things guys are doing. I bought mine because of the possibilities but ALSO because all the work I do is small stuff in brass and aluminum and the machine works well for this. Its not a heavy duty machine, but I like it. The one problem I have with tightening the quill is not a biggie because there are videos (search hoss machine) showing how to take the quill apart etc for upgrading the bearings etc. You can get all kinds of online help with this machine, just not from King. I think grizzly ships to Canada now so you might want to look into that too. Busy Bee sells a version of this machine but the table is miniscule by comparison, I went for the bigger table.

 

[mattthemuppet2]

The PDM30 might be bigger and have a longer quill stroke, but you'll lose zero everytime you have to raise or lower the head. There are work arounds, but it doesn't make sense to start with a machine you have work around if you're paying new.

The PM727 is a worthwhile alternative in my book - it's what I'd get if I had the cash.

 

[HBilly1022]

Hbilly

One thing you might want to do is a search on the G0704 and see what all the cnc guys are doing with this machine and the kind of parts they are making. There are home upgrades for power, cnc conversion, it amazing all the things guys are doing. I bought mine because of the possibilities but ALSO because all the work I do is small stuff in brass and aluminum and the machine works well for this. Its not a heavy duty machine, but I like it. The one problem I have with tightening the quill is not a biggie because there are videos (search hoss machine) showing how to take the quill apart etc for upgrading the bearings etc. You can get all kinds of online help with this machine, just not from King. I think grizzly ships to Canada now so you might want to look into that too. Busy Bee sells a version of this machine but the table is miniscule by comparison, I went for the bigger table.

Wayne, I'm not sure what I will use the mill for but I'm pretty sure that 99% of the work I will do would be with steel. I note that you do mostly small stuff and use softer metals but some work with stainless. How does the 20 handle it? Do you think it would be good with heavier use in mild steel? I've looked at Grizzly stuff over the years and wish there was one in Canada. With our dollar being so low right now I won't be buying anything from south of the line unless there is a super sale on. I looked at the Busy Bee stuff too and as you noted the tables on there machines are much smaller until you get into the more expensive mills and I'm not prepared to spend a bunch of money for something I will likely only use periodically. I've even thought of getting my lathe set up to do some small milling but it just makes sense to get a dedicated mill. I checked out the King website and looked at the owmers manuals for the 20 and the 30. The 20 manual looks pretty decent but the 30 manual is almost useless. Looks like it was printed a decade ago and the translation to English is terrible.

The PDM30 might be bigger and have a longer quill stroke, but you'll lose zero everytime you have to raise or lower the head. There are work arounds, but it doesn't make sense to start with a machine you have work around if you're paying new.

The PM727 is a worthwhile alternative in my book - it's what I'd get if I had the cash.

Not having used a mill yet, I'm don't understand the issue of loosing zero when the head is moved. Wouldn't the same issue be a concern with the 20? From what I recall the DRO reads the movement of the quill, so if the head was lowered with the 20 wouldn't zero be lost too? And since the 20 only has 2" of travel the head would need to be moved more often than the 30. Am I missing something? Another question is; does the 30 need to be trammed every time the head is moved up or down? I would think that would be a much bigger issue, if it was in fact necessary.

 

[hman]

Not having used a mill yet, I'm don't understand the issue of loosing zero when the head is moved. Wouldn't the same issue be a concern with the 20? From what I recall the DRO reads the movement of the quill, so if the head was lowered with the 20 wouldn't zero be lost too? And since the 20 only has 2" of travel the head would need to be moved more often than the 30. Am I missing something? Another question is; does the 30 need to be trammed every time the head is moved up or down? I would think that would be a much bigger issue, if it was in fact necessary.

I have an RF-30 clone (round column mill) myself, and I'll be glad to explain the zero issue. It comes from the fact that the column is round. Every time you find that there's not enough quill movement (like when you want to mount a chuck in the spindle) to do what you want, you have to loosen the head and raise or lower it. On a dovetail (or "square column") mill, the dovetails keep the head in the same X-Y position as it raises and lowers. There is no such feature on a round column. So every time you even loosen the head, you lose the original X-Y position of the spindle.

There's been plenty of schemes to keep the head aligned or alignable, but none of them have enough precision (say +/- .001" in both X and Y) to be of any use. What you have to do every time you move the head is chuck up (or collet up) the 'ol edge finder and re-establish the 0,0 reference point. If you have a DRO, that's just a button push. If you're using dials, you have to reset them.

PS - as for losing Z zero, you're right about that, too. But it's a lot easier to re-establish than X-Y.

I did find one other comment on another thread where someone stated that the head of his RF30 clone had a tendency to twist because it was mounted on a circular column instead of a dovetail one. I have no experience with mills so don't know if this could be an issue or not. Seems to make sense though.

That comment might well have been related to what I've explained above. OTOH, if the comment was meant to imply that the head would move around while milling, I'd say this guy simply didn't properly tighten the two bolts that retain the head! I've NEVER had anything like this happen.

PS - Another possible issue with round column mills is tramming. There is no provision on the mill for setting or re-adjusting tram. If you're out, you have to remove the (heavy!) head from the column, dismount the column from the base, and then add shims (generally a cut-and-try method). Theoretically, the mill is in good tram when it leaves the factory, so this is not too common an issue. I've also heard reports of having the head trammed perfectly at one height, and discovering that it's not so good at another height. I've not experienced this myself, but then, because I don't have a "real mill," I don't try to fool myself that I can achieve anything better than +/-.001" (or maybe +/-.002"?) accuracy.

I don't know what related or unrelated issues might come up with a square column benchtop mill. And I expect it will be a LONG time before I can even think of affording a knee mill (what lots of folks call a "real" mill). I'm very well satisfied with my RF-30 clone. I'm also satisfied with my Harbor Freight 44991 mini-mill (with goodies added, of course).

Best wishes, whichever way you decide to go.

 

[HBilly1022]

I have an RF-30 clone (round column mill) myself, and I'll be glad to explain the zero issue. It comes from the fact that the column is round. Every time you find that there's not enough quill movement (like when you want to mount a chuck in the spindle) to do what you want, you have to loosen the head and raise or lower it. On a dovetail (or "square column") mill, the dovetails keep the head in the same X-Y position as it raises and lowers. There is no such feature on a round column. So every time you even loosen the head, you lose the original X-Y position of the spindle.

There's been plenty of schemes to keep the head aligned or alignable, but none of them have enough precision (say +/- .001" in both X and Y) to be of any use. What you have to do every time you move the head is chuck up (or collet up) the 'ol edge finder and re-establish the 0,0 reference point. If you have a DRO, that's just a button push. If you're using dials, you have to reset them.

PS - as for losing Z zero, you're right about that, too. But it's a lot easier to re-establish than X-Y.


That comment might well have been related to what I've explained above. OTOH, if the comment was meant to imply that the head would move around while milling, I'd say this guy simply didn't properly tighten the two bolts that retain the head! I've NEVER had anything like this happen.

PS - Another possible issue with round column mills is tramming. There is no provision on the mill for setting or re-adjusting tram. If you're out, you have to remove the (heavy!) head from the column, dismount the column from the base, and then add shims (generally a cut-and-try method). Theoretically, the mill is in good tram when it leaves the factory, so this is not too common an issue. I've also heard reports of having the head trammed perfectly at one height, and discovering that it's not so good at another height. I've not experienced this myself, but then, because I don't have a "real mill," I don't try to fool myself that I can achieve anything better than +/-.001" (or maybe +/-.002"?) accuracy.

I don't know what related or unrelated issues might come up with a square column benchtop mill. And I expect it will be a LONG time before I can even think of affording a knee mill (what lots of folks call a "real" mill). I'm very well satisfied with my RF-30 clone. I'm also satisfied with my Harbor Freight 44991 mini-mill (with goodies added, of course).

Best wishes, whichever way you decide to go.

Thanks John, great info there. I never thought about the x y being lost and now that you explain the issue I can see this could happen frequently and it would be a hassle. I don't know how to use an edge finder but if I end up getting the 30 I guess I will have to get one and learn how to use it.

 

[hman]

An edge finder is pretty much essential for any milling task on just about any mill. It lets you establish exactly where your part is located.

Easy enough to use. Usually they have a ½" diameter shank and an extension that's a very precise 0.200" diameter. You chuck it up or hold it in a ½" collet and run the spindle at a few hundred RPM. With the edge finder a bit outside the edge of the part, lower it so the end is a bit below the top surface of the part. Slowly crank the part toward the edge finder. Initially, the extension may or may not be centered. As the part approaches, the extension will first center itself. Then when it makes first contact with the part, it will suddenly (almost magically) shift to one side. At that point, the center of the spindle will be exactly one radius (0.001") away from the edge of the part. The first few times you use one, you'll probably want to run it back out, then back in very slowly the last few thousandths, so as to avoid going past the magical point.

Once you have the 0.100" position, you can raise the center finder clear of the part, move the table exactly 0.100" toward the spindle (using the DRO or the graduated dial on the crank), and set your X or Y zero. Repeat for the other axis. The whole process is almost faster than reading about it. There are probably some youtube videos on how to use an edge finder that you can watch if you find my description at all unclear.

As I said in a previous post, I have a round column mill, and it doesn't really bother me too much. But then, I don't tend to get in a big hurry.

PS - Rick Sparber, another member of this forum, also has a round column mill. He's written a goodly number of articles over the years. You can find them at http://rick.sparber.org/ma.htm#4

Two that might be of immediate interest to you are:
http://rick.sparber.org/msu.pdf
and
http://rick.sparber.org/mhp.pdf

 

[HBilly1022]

John, your explanation is crystal clear and many thanks for that. Also thanks for those links. There is a wealth of info there and will keep me busy reading for a while.

Do you find yourself needing to re establish zero during most projects or is this something that only occurs occasionally?

Based on all the info received so far, my biggest concern would be tramming. I had to Google what that meant and found a site where someone had a very difficult time getting his round column trammed and it took him weeks trying different things before he finally got it. I hope that is highly unusual but if it's going to happen to someone it will likely happen to me. I had a lot of issues with my new King lathe and don't expect the King mill would be any different.

I'm really conflicted with these 2 choices. The 20 ($1600) is a 4.8 amp 110V machine (528W) and the 30 ($1800) is 11A @ 220V (2420W). The 30 weighs twice as much as the 20 and the 30 comes with some essentials to get started. The negatives with the 30 are the round column, lack of quill DRO and belt drive vs VS. If I bought the 20 it would cost me more than the $200 difference to buy the equipment that comes standard with the 30. So equally equipped the 20 would cost more.

Looks like more reading is required.

Please excuse my OCD. I obsess about decisions like this until the money is spent, then all is well again.

 

[WayneP]

Wayne, I'm not sure what I will use the mill for but I'm pretty sure that 99% of the work I will do would be with steel. I note that you do mostly small stuff and use softer metals but some work with stainless. How does the 20 handle it? Do you think it would be good with heavier use in mild steel? I've looked at Grizzly stuff over the years and wish there was one in Canada. With our dollar being so low right now I won't be buying anything from south of the line unless there is a super sale on. I looked at the Busy Bee stuff too and as you noted the tables on there machines are much smaller until you get into the more expensive mills and I'm not prepared to spend a bunch of money for something I will likely only use periodically. I've even thought of getting my lathe set up to do some small milling but it just makes sense to get a dedicated mill. I checked out the King website and looked at the owmers manuals for the 20 and the 30. The 20 manual looks pretty decent but the 30 manual is almost useless. Looks like it was printed a decade ago and the translation to English is terrible.



Not having used a mill yet, I'm don't understand the issue of loosing zero when the head is moved. Wouldn't the same issue be a concern with the 20? From what I recall the DRO reads the movement of the quill, so if the head was lowered with the 20 wouldn't zero be lost too? And since the 20 only has 2" of travel the head would need to be moved more often than the 30. Am I missing something? Another question is; does the 30 need to be trammed every time the head is moved up or down? I would think that would be a much bigger issue, if it was in fact necessary.

Hi HBilly

You've gotten great answers on the zeroing. As to the mills ability on machining steel I don't really know as I seldom if ever machine it. On the stainless I use 1/4" diameter cutters with small cuts so its not much of a challenge. I still say that the best way is to research the guys converting these machines to CNC and have a look at their projects, see what they're making. (pm me if you can do that here and I'll send you some info on places to look). I'm sure they're doing steel parts. The thing I like about the mill I bought is that I can crank the head up and down when necessary and not lose my zero. It saves me a ton of time.

 

[HBilly1022]

Thanks Wayne, I looked at the Grizzly G0704 again and at some videos of it on you tube. The biggest issue for me though is that the G0704 has a 12 Amp motor and the KC-20VS only has a 4.8 Amp motor. So the Grizzly is 2.5 times more powerful than the KC so the Grizzly videos really aren't that helpful. I've tried looking for some youtube videos of a comparable Craftex and only found one of the CX600 ( a 600W machine) that shows a guy drilling a hole and it appeared the mill was struggling. The Kc-20 motor is slightly smaller than the Craftex so I would like to find some video of a 500W to 600W motor doing some milling in steel to see how it performs. I have no intention of converting to CNC so none of that interests me (well at least not right now). From the few vids I've seen so far the G0704 seems to have enough power for what I expect to do and would be happy with that. I just don't know how well the smaller King motor would perform in steel though. I'm still looking for vids of something similar.

Going back to the city tomorrow and will stop by the tool store to look at the 2 King mills again. Unfortunately the staff there aren't much help and really don't know much about mills or lathes. They just sell them.

 

[WayneP]

Thanks Wayne, I looked at the Grizzly G0704 again and at some videos of it on you tube. The biggest issue for me though is that the G0704 has a 12 Amp motor and the KC-20VS only has a 4.8 Amp motor. So the Grizzly is 2.5 times more powerful than the KC so the Grizzly videos really aren't that helpful. I've tried looking for some youtube videos of a comparable Craftex and only found one of the CX600 ( a 600W machine) that shows a guy drilling a hole and it appeared the mill was struggling. The Kc-20 motor is slightly smaller than the Craftex so I would like to find some video of a 500W to 600W motor doing some milling in steel to see how it performs. I have no intention of converting to CNC so none of that interests me (well at least not right now). From the few vids I've seen so far the G0704 seems to have enough power for what I expect to do and would be happy with that. I just don't know how well the smaller King motor would perform in steel though. I'm still looking for vids of something similar.

Going back to the city tomorrow and will stop by the tool store to look at the 2 King mills again. Unfortunately the staff there aren't much help and really don't know much about mills or lathes. They just sell them.

Good point you make about the motor power. When I bought the machine from KBC tools in Windsor Ontario they warned me it was a "light duty" machine and perhaps this is why. I have a bigger benchtop mill that I also use and it has a bigger motor on it which I use for bigger x-y stuff so I'm not concerned. If you're only going to have one mill I guess bigger is better. The motor on this smaller King machine is a variable speed type and there is a small speed control knob and readout to indicate the speed. Interestingly...the CNC conversion guys show a re-powering mod for this mill where they put larger motors with appropriate variable speed controls which they can then control with their CNC software, very interesting. There are aftermarket kits available to re-power this particular machine believe it or not and its what I'll do if/when I ever have trouble with the motor.

The advice you're received about zeroing is good though so if you get a bigger machine make sure you can raise and lower the position of the head (or table) so that you don't lose your zero.....unless of course you don't mind spending the time to re-zero manually every time.