Tool Escalation via Rationalization
January 23rd, 2009I Must Own All Tools
Is this a beautiful day, or what? It’s too cold to sweat, it’s too dry for the mildew to grow, and the sun is out.
I appreciate the information people have sent me on milling machines.
It’s funny how my “needs” have changed. First, I thought I needed a drill press. Then I learned that a mill would do 98% of what a drill press would do, plus a whole lot more. And I learned what a good drill press costs; if you don’t spend at least $600, you are not buying a lifetime machine that will do metal and wood well. And $1000 is more realistic. That’s a lot, just for holes and sanding.
So I started looking at mills. I was pretty excited about small “mill drills.” Then I learned that they cost roughly the same amount of money as huge mills that will do almost anything, because there are lots of used industrial milling machines out there. And I’d be willing to bet that a 40-year-old industrial mill will outlast a brand new Chaiwanese mill/drill, and I know it has a better resale value.
I thought a Millrite would be a good choice, because it’s big enough to do a lot, but you can fit it in a garage fairly easily. But then I learned that they don’t cost much less than Bridgeport Series I mills, which are better and probably easier to get parts for.
It looks like there is a price envelope, including shipping and taxes, of $1500-$2500, no matter what I buy. You can spend more, but this seems to be what you should pay for a good used machine, if you’re willing to fix it up a little.
One big problem: I am incompetent to evaluate a used milling machine. Jdunmyer sent a link to a helpful site, but even if I applied the information, I would probably make mistakes. Also, a lot of the deals out there are beyond my normal driving range, so I can’t really get to them to look them over.
I keep reading about backlash. I’m not totally positive what this is, except that it introduces error into table movements. It sounds like you crank the table to a certain position, and then it backs up on its own. It’s supposed to be a problem on old machines. Can you correct it? I do not know. Can you work around it? I do not know.
Maybe the best thing is to get a cheesy drill press and use it until I get a deal in which I can have confidence.
Here’s an interesting buy. Someone in the Tampa area has a Bridgeport mill which can be had for $1250, meaning it can be in my garage for maybe $1700. The ad has expired, but I have a feeling they would relist it. It’s 3-phase, which is good, but it has a 3-phase feed motor, too, which means I’d have to replace it and use 2 cords, or I would have to find a way to run both motors from a VFD, or I would need a VFD plus a converter for the feed motor. I guess that would be a problem with any 3-phase mill that has a second motor. Do I even want a feed motor? Can you use a mill as a drill press when it has a feed motor?
There is a local dealer with a Millrite, but they want $1950, which seems very high. A lot of people pay two grand for these machines, but many people pay half of that, and the economy is not good, and it’s not going to get better for a very long time, if ever. Prices on used industrial equipment should be plummeting, unless the Chicoms and Indians are buying it for export. I very much doubt that they have any interest in it. They make their own equipment much cheaper.
A guy in Texas has one for a grand, but when you add the other expenses, it’s $1700, and it appears to be pretty old, and I can’t inspect it.
The nice thing about a mill is that it should be the last really big tool I’ll ever need. I could always add a lathe eventually, but I should be able to get by without it very well.
I think I’m finally in a position to make a few things, or at least I will be when my bandsaw table pin arrives. I have been occupied with other stuff this week. I may run over to Shell Lumber and see what they charge for hardwood boards. I really need some metal for a bandsaw base. I think I’ll just make a frame with 2″ angle iron (not perforated) and then cut small pieces of angle iron for tabs through which I can run the bolts for casters. I assume angle iron this big would be sturdy enough. Each tab would have to support about 110 pounds, even with work on the table.
I don’t understand how the stabilizing doodads on my table saw’s HTC3000 mobile base work. They are supposed to rotate little feet down onto the concrete to stabilize the saw, but when I screw the feet up as high as they will go, they are still so low they would raise the saw quite a bit if they were lowered. And that means there is tremendous resistance when I try to use them, so it appears to be impossible to make them work. The plastic levers that operate them would snap. I don’t really need them. The saw’s four other feet have brakes. But I wish they worked.
A guy with a welder and some cutting tools (i.e. me) can make a nice mobile base with locking feet. A guy with a welder and some cutting tools and a mill can make little cammed things that lower the saw and stabilize it. Unfortunately, that guy is not me.
Not sure how I’m supposed to get the saw off the ground to lower it onto the base. I think my hoist will do it, but there is always a possibility that 367 pounds will pull the garage roof down. Probably not. The saw has a weird eye in the top of it. Is that for lifting? I don’t know what else it could be for.
My Incra V27 miter gauges arrived. My bandsaw had no gauge when I bought it, and the table saw had two really bad ones. These look good. They’re supposed to be very precise, and you can adjust the slop with a hex wrench. I can save the old ones for permanent jigs or something. The one on my portable saw is okay, but I don’t believe in moving accessories from one tool to another when it’s avoidable.
Lots of stuff to think about today. Lots to do. But it sure beats thinking about how I can’t do anything because all of my tools are Chinese junk in a little Rubbermaid toolbox.
Also, I have a great idea for a new book.
January 23rd, 2009 at 10:14 AM
YES. Write your book about going from a non-tool-guy to a master of your own domain.
I will never forget your comment about how so many white collar kids have dads who are clueless about this stuff, so they have to learn about them where they learn about drugs and guns – on the streets.
Oh yeah. With a mill you can make your own firearms. Just saying.
January 23rd, 2009 at 11:41 AM
As a retired tool & diemaker here is how I see it. If you have room for a Bridgeport, or a full size knee mill (which it is) go for it, they are very versatile. Backlash is the amount of free play back and forth in the lead screws that move the table-saddle. It is easy to learn how to work around it, and can be reduced with some new parts (lead screw and nut), or if you latter decide to put a digital readout on your machine you forget about it and use the readout for all your positioning. Mills work very nice a drill presses but not the opposite. Tooling and parts for a Bridgeport are plentiful.
I don’t have a knee mill because I don’t have room, all my space is in the basement, and it about killed my to get a 9” South Bend Lathe down there. Personally I am looking at one of the Grizzly mini-mills, otherwise I would not think twice about a Bridgeport. You might want to start looking at the Practical Machinist web site, a message board where you can ask questions and get answers and suggestions from other members.
There is an exception to every situation mentioned above but this is my .02.
January 23rd, 2009 at 11:46 AM
Why, yes. Yes it is a beautiful day. Downright “balmy”, as the weather dudes keep saying, with a high of 34.
January 23rd, 2009 at 12:44 PM
Put a nut on a bolt. The junkier the better.
Push the nut back and forth axially along the bolt. You will feel it move, just a little. That’s backlash.
The nuts and bolts that operate the table on a milling machine are much more sophisticated, but the principle is the same. What that means is, for measurements using the handles and dials to be accurate you always have to turn them the same direction. If you go to position number 1 by turning clockwise, you have to go to position number 2 by turning clockwise. This often means turning anticlockwise beyond the position you want, then clockwise to get to the accurate position.
The table has V-shaped “dovetails” that guide it. The dovetails have gaps, which are filled by pieces called “gibs”. If everything is tight and correctly assembled, there is enough friction that the table won’t move under normal vibration. You do have to be careful when cutting sideways. The work pushes back on the tool, and if the slop is in the wrong direction the table can move.
All real machines have some backlash. There are ways you can adjust backlash out in some cases, but if you go too far it increases the friction, which promptly wears the nut and/or screw so as to create new backlash. Accommodating backlash is just part of learning how to use the machine.
Digital readouts don’t use the screws. They have an independent means of measuring table position, and when using one concerns of backlash have almost entirely to do with which way the table is likely to be moved under tool pressure.
If you can find a way to supply power to the table feed, by all means get it. Especially when you are cranking it up and down, it can get very tedious to move it far by hand.
Regards,
Ric
January 23rd, 2009 at 1:09 PM
And — let me endorse & repeat suggestions made elsethread, viz., the tool you need most in order to go forward is workspace.
Adding a full-sized milling machine to your garage is going to leave the T-Bird outside, at least if you plan to do anything. A milling machine is not something you can put on a rolling base and move in and out as needed. For one thing, it’s way too heavy. For another, it needs to be bolted down solidly in order to work right.
Space to work in is as much a “tool” as anything you can hold in your hand or put 240 3-phase to. What you need to be doing now is not browsing tool catalogues, it is contacting real-estate agents looking for Central Florida properties — nice but not ostentatious house, a good-sized shop building, decent electrical, telephone, and data services, and enough land to put up a small shooting range. You obviously have enough money to meet your small needs. Use it to get the tool you need most: space for tools.
Regards,
Ric
January 23rd, 2009 at 1:39 PM
RE room for tools: http://igor.chudov.com/projects/My-Bridgeport-Mill/Mobile-Bridgeport-Mill-Base-On-Casters/
January 23rd, 2009 at 2:10 PM
Book: yes please! (Assuming it’s a set-up-your-shop how-to or something similar.) I am at least 5 (probably 10) years away from being able to follow a similar path, and by then these blog posts will have dropped away from memory. (Who am I kidding, in a month I’ll forget what a DRO is). My dad is handy by some standards and taught me what he could, but I’m nowhere near the “fabricating” standard, unless you count stained glass lamps and model airplanes. (I have a machinist/geography-teacher uncle who could help, but he’s too far away and works too hard to pick his brain regularly.)
January 23rd, 2009 at 3:16 PM
Yup. Very pretty. Inventive. Ingenious, even.
So the procedure is:
1) Back the T-Bird out of the garage.
2) Pull the milling machine into operating position.
3) Level the milling machine (call it half an hour)
4) Remove the front bar of the carriage (so you don’t trip)
5) Make your cut.
6) Re-attach the front bar of the carriage.
7) Let the mill down off the levelers so it can be moved.
8) Push it back into storage position.
9) Park the T-Bird again.
10) Discover you need to make another cut. GOTO 1
It can be done. If you’re willing to put up with it, it will be done. I just don’t see it as a practical proposition.
Regards,
Ric
January 23rd, 2009 at 3:58 PM
My drill press cost $60 at Harbor Freight.
It drills holes in things. I consider it money very well spent.
Now, it’ll wear out before a $600 drill press. But I can buy ten of them, with a much lower opportunity cost.
January 23rd, 2009 at 4:31 PM
Actually, you leave it in the front corner of the garage, and you use the mobile base on the rare occasions when you need to turn it to mill big workpieces.
.
I don’t think it will take me half an hour to adjust four leveling bolts.
January 23rd, 2009 at 7:37 PM
Feeder motors are nice, but not needed. If you don’t have one on the z-axis, you can adapt a socket to replace the crank with a drill motor for those times you need to raise and lower it a few inches. Gib wear can be overcome by snugging the handles that lock the table from moving. Not perfect, but cheap.
The big expense is the drive train. If that doesn’t sound right, walk away. If you buy a used unit, the guy has to have tooling he won’t be needing anymore.
If you have to move the Bridgeport, an easy way would be to attach two “ears” on the base high enough off the floor to get a floor jack underneath each one. Jack the mill up enough to overcome friction and pull. Or weld rectangular tubing on in place of the “ears” and lift with your hi-lo forks.
You need a hi-lo.
Nicew to see Freddie here.
January 24th, 2009 at 8:40 AM
Better then a hi lo would be fork attachments for the Bobcat.
Just sayin.
January 24th, 2009 at 12:03 PM
This is good info as I plan on looking for a machine sometime soon.
Two years ago, I needed a drill press. I looked at $60 presses. I looked at $600 presses. I opted for the $600 because of the slower spindle speeds that were available, which are necessary for large holes.
January 24th, 2009 at 2:03 PM
Leo,
Most BobCats don’t have self-leveling buckets/fork attachments, so a Hi-Lo is better. “just sayin'”.
Steve,
It sounds like the B’Port you’re looking at has a genuine B’Port power feed, which does have a 3-phase motor. It also has a speed-shifting gearbox. Although I’ve never actually used one of those, if it was my mill, I’d replace it with a modern power feed like this one: http://www.use-enco.com/CGI/INSRIT?PMAKA=307-3693&PMPXNO=8741198&PARTPG=INLMK32 You really only need a power feed on the ‘X’ axis (table feed), and it will remain unused by you until you start doing serious projects.
It’s unnecessary to level a B’Port, just make sure it’s sitting on all 4 corners. However, it’s nice to have it level (as in with a machinist’s level) so stuff doesn’t roll off the table and so you can use that machinist’s level for setup purposes in some situations.
Ric gave you a very good explanation of backlash, and pointed out how little it really matters, especially if you have DROs. More important than backlash is wear on the dovetails that the table and cross-slide move in: when winding the table back and forth in the middle of its travel, it should move pretty easily, yet have little play. Grab the ends of the table and pull/push like you’re trying to spin the machine around. There should be little or no play. Now, wind the table sideways in each direction. Unless the machine is exceptionally unworn, it’ll get tighter/harder to turn towards the ends, as the dovetails are less worn there. Wind the cross-slide back towards the column and forwards toward you and you’ll probably find the same thing, tight at the travel extremes, easy movement in the middle.
It’s very difficult to describe what is “too much wear”, bear in mind that you can do good work on a very badly worn machine. It’s very expensive to get the ways rescraped so as to eliminate the wear, so it’s best to buy something that’s not worn out. Best to inspect several machines before buying, if you can.
Although the Practical Machinist BBS is good, they’re oriented towards the pros. Better for us HSM guys is the Home Shop BBS at http://bbs.homeshopmachinist.net/ There’s some very knowlegable people in both places.