Shim session 1

Hello all,

For reasons that are beyond my comprehension, I loosened the bolts, scraped out what I could between the column and the base, swept the table, and added some shims. Actually, I swept the table as a test before ever messing with the bolts.

First, my Chinese combo wrench was no match for the Chinese lock washers. Geeeezzzzzz. Hats off to Enco, because their bargain wrench (23 mm was the charm) held very securely, allowing me to use my bargain deadblow hammer.

The readings matched what I expected from the face mill: the head was leaning to the right (almost a shame to fix it). I was a little surprised to find about seven thou at 5 inches. At this point, I have it within a couple thou, and should get more shims before messing around any more. The alignment should be much improved, and I doubt I have the material to do better.

So far, I am using all one-thou shims. Would you like me to get some thicker ones? While I'm at it, are there any cheap but good indicator holders I should get? I cobbled together a contraption using parts from the Baker kit and at least one import mag base. Maybe that's good enough. Most of my dti work is spindle mounted for aligning my vise, and that is easy (slap it in a collet) and works well.

To tighten the bolts, I gave them a good tug and then a few light whacks with a mallet. Was that overkill? They were _really_ tight before I got to them. Do I need to do something else? Having seen a vise slip, I have renewed respect for milling forces, but obviously, stripping those bolts would be a BAD idea =:0

Bill

Reply to
Bill Schwab
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If you can put a shim in that is the proper thickness and you have one on hand, it makes screwing around with the job easier because you don't have to keep chasing the shims to keep them stacked properly. Otherwise, if you've kept things clean, shouldn't make any difference.

When you shim the base, try to install the exact amount of shim that the position requires------which is much easier if you have the .001" shims you mentioned, otherwise it requires a variety of shims---not really necessary.

I've always used the attachments that came with my indicators, but when I need something beyond normal application I use the large unit that came with my Starrett mag base. By chucking a short piece of 3/8" diameter material I can then use pretty much any kind of extension needed. I'm not sure what the new ones look like, but mine has a large knurled nut that unlocks the swivel that accommodates two 3/8" rods---which you can then place at any angle you prefer. Hope this makes sense. It does when you're holding the attachment. Beyond that, I have no suggestions.

Agreed, stripping them would be a bad thing, but it might be a good idea to check proper torque specs for the diameter bolt in question and use a torque wrench. Breaking the bolt wouldn't be nearly as bad a deal as having the head move under a cut. If you do use a torque wrench, unless you can ascertain that the bolts are heat treated, tighten them to specs for a class

2 bolt. That's playing it safe. I'm not sure how I feel about using a hammer on the threads. I've always just trusted my instincts when tightening bolts, but then I've tightened one hell of a lot of them.

Harold

Reply to
Harold and Susan Vordos

Harold,

I'm close as it is, so I will probably stick with one thou.

That helps. I will find the isolated pieces that I need to make a dedicated rig; it should be a lot cheaper than the complete sets and will prevent lost parts and time.

"Hammer on threads" makes it sound worse than it was: I used a soft dead blow hammer on the end of medium length wrench. It took a lot more of a whack to get them loose than I used to tighten them; each of them took three light taps with progressively less motion each time. I will check on class 2 bolts; that sounds a lot nicer than winging it. Somehow, I suspect I will need a bigger torque wrench than the one I have on hand for small engines [*].

[*] Don't get the idea that I know what I'm doing; I'm simply too lazy to cart a mower off for service :)

Thanks!!

Bill

Reply to
Bill Schwab

Damn, late last night I was thinking about my response and wondered if I said. I meant to say *grade* 2. Class is a reference to the thread itself, not the strength of the bolt (which will automatically have a class

2 thread).

The reason I suggested grade 2 bolts is because of the unknown with the existing bolts. They may not be heat treated. The torque specs for a grade 2 would be lower than for a grade 5 or grade 8 bolt. If the thread depth in the casting is double the diameter, if you buy new ones, shoot for stronger bolts. Grade 2 is the lowest, just plain low carbon steel.

The only problem I had with the soft blow hammer is that it's hard to know how much you're putting on the thread, but if you have a sense of how much is too much, go with it. Didn't mean to imply it was wrong, or a bad way to go, it's just that torque wrenches remove the unknown.

Harold

Reply to
Harold and Susan Vordos

Harold,

No sweat; I'm actually happy it's a concept with which I was already familiar.

That's a good way to look at it. Beats an educated guess with a hammer :)

I appreciate the feedback. Given how hard it was to get the bolts loose, I had to do something beyond pull on that wrench, and I didn't have a workable extension. I did some milling yesterday (including some deep cuts in Al), and some flycutting today; no disasters yet =:0

With the flycutter, I can already see a massive improvement in the alignment. Suddenly, the "leading and trailing edges" both typically leave marks on the surface. I won't claim that it's dead nuts yet (pretty sure it's not), but it is probably not off by much.

Bill

Reply to
Bill Schwab

Cool! That's what you're looking for.

My experience with mills indicates that you'll never get it "perfect". There's rise and fall to some degree in almost all tables, so you get a changing pattern, but on the average, you don't want a lip where cuts overlap. It will always show a difference because of the variable feed rate, almost non-existent at the edges of the cutter, and the coarsest @ 90 degrees. I think you get my drift. Bottom line is when the head is correct, you don't get steps. That's the target, anyway. The cross-hatch you mentioned as an excellent indicator that the head is correct in one plain. When you can duplicate that pattern by moving the saddle, the head has to be true.

Sounds like you're getting a handle on the machining thing, Bill.

Harold

Reply to
Harold and Susan Vordos

Harold,

It was nice to see.

Agreed. It if looks perfect, get a better indicator ;)

I think so.

That sounds like a good test. I'd either need something long enough to clamp on either side of the test area, or I could turn my vise. I don't remember whether the bolt slots align with the t-slots near 90 degrees, but I could put the angle base on it long enough to try it. The vise would not need to be precision aligned at 90 degrees, right?

You and others here have been a huge help. Thanks!!

Bill

Reply to
Bill Schwab

head is correct in one

Right, unless you intend to do other work on the item in question, mill edges or other features, drill holes, etc. For surfacing, it clearly isn't important. I do like to have it close, though, so if more than one pass is taken there's not a tell tale line that shows the part wasn't square with the cut. Often times I have to use both the saddle and table for items, which may even be clamped to the table. think of surfacing a large casting that accepts a lid, for example.

Some vises have slots or holes at the ends, so you can install the vise sideways. If not, use finger clamps. Not necessary to use the holding bolt positions unless the vise isn't flat, and even then you can clamp near enough to pull it down with just a little luck.

Harold

Reply to
Harold and Susan Vordos

Harold,

That makes it fairly painless to clamp someting for facing with the saddle. I'll probably try it the next time I have reason to take down the vise.

I've been surprised by the number of things I've ended up clamping to the table (often with wood or blocks). Some of that might be due to having only a four inch vise. It has also come up with very thin parts, though they could be mounted to a sub-plate in a vise.

I should have thought of that - early on I used clamps to hold my vise because I didn't have bolts for it.

Thanks!!

Bill

Reply to
Bill Schwab

Welcome!

Harold

Reply to
Harold and Susan Vordos

Breaking a few bolts and stripping a few threads with misc wrenches and sockets is a priceless learning experience. The more difficult it is to fix/replace said broken item the faster one seems to learn (at least for some of us, there are those that never seem to figure it out).

A man has to know his limitations and strength.

Here's a few torque charts I found, just in case you didn't dig one up yet:

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or if previous link with the embedded space doesn't work:

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and a metric chart:

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Reply to
Leon Fisk

Leon,

True enough, but let's _not_ try it on my milling machine, ok :)

numerous and indefinite

few and defined :)

Thanks!!!

Bill

Reply to
Bill Schwab

Harold,

I think I was making this a lot harder than necessary. Do you care how much motion there is in the saddle, or merely that a given strip of metal "sees the entire flycutter"? Assuming the latter, and needing to face a small block, I did some roughing with a 3/4 endmill and then ran the flycutter over it (queue drum roll) using the saddle: I got a cross hatch pattern :)

Unless I am missing something, I plan to leisurely buy another pack of shims, and _not_ bother using them until I see a problem. Do you agree?

Bill

Reply to
Bill Schwab

Two things should come together. Your indicator, when swept in a circle that covers the majority of the table surface, front to back, shows little, if any deviation from your set point, and you get cross hatch when you machine in both plains, you can assume that your mill is as close as it's likely to be. As we both agreed, it will never be perfect-----it lacks the kind of precision required----as do knee mills. If you're happy with how your mill performs, I'd suggest it's fine. Remember, the amount of error you see on your indicator translates into how holes lean, assuming your parts are mounted to the table. Conventional machining requirements dictate that such things have a common tolerance of .001"/inch, so if the mill head is within a thou or two over six inches, you're well within acceptable standards, although I prefer to be closer. I try to keep the indicator within less than a half thou, but on a knee mill you don't really know what is correct. Knee sag can be very deceiving.

Yep, I do. Especially considering the fact that you're learning----and are likely to make mistakes that are far greater than the capability of your machine. Hope you understand I'm not trying to be rude. It takes lots of skill to make good parts, and you lack experience at this point. As you progress, many things that may not be obvious to you now will come into sharp focus----at which time you may find fault with some of the decisions you make now---so keep an open mind and consider that you're likely working with a machine with capabilities beyond the skills you possess as a craftsman. Hopefully that will change rapidly. That's really what it's all about. Truth is, you'll know when the machine isn't up to your standard, or requirements.

I think you're doing fine, Bill. What impresses me more than anything is your ability to be told, and that you listen. Makes it worth my time to try to help.

Harold

Reply to
Harold and Susan Vordos

Harold,

I will certainly take another look at it. Having some more shims on hand first would be a good idea, and I want to dig into the torque specs before messing with it again.

No offense taken - you've been very helpful, and the spirit of the comment is clear, and quite correct.

For example, I more exerienced machinist would not have broken a tap in the near complete part yesterday - it was going so well... I need the thing, and didn't want to waste time and metal scrapping it, so I drilled another couple of holes and milled off the burr that could have caused injury.

Whoa! I just looked at my watch =:0 I was planning to bump in my vise using only the fixed jaw. Based on what I saw when indicating off of that block I was using, I suspect there might be something fishy with my vise or jaws. Hopefully anything out of whack will be easy to correct, and even in the worst of scenarios, it has nothing to do with the mill.

There is an intermittent vibration that either gets cleared up by adjusting the gibs or is randomly coming from the motor. Given the hour and what I still need to do, I have made a note to describe it separately.

The bottom line is that it is quite a nice machine. In just the past few days, it earned all the electricity and vactra it wants for the next six months :)

I'm getting a lot out of it. Thanks!!!!

Bill

Reply to
Bill Schwab

and you get cross hatch when you

Just noticed my misuse of the word "plains"-------and I expect I've been getting lots of miles out of it. I know it should be plane------but once I get something in my head, right or wrong-----sigh!

Chuckle! Sorry about the tap, but if you think having experience exempts you from breaking taps, you're never going to feel like you have any-------(experience, that is). They break, and usually at the worst time, although I can't imagine when a good time might be.

It might be worth a mention-----if you're trying to power tap with a hand tap, breakage is almost guaranteed. They don't provide proper chip control without reversing them at the most, every half turn. Make sure you do all your power tapping with power type taps.

If you have a good vise, say a Kurt, the jaws are usually thick enough (and generally straight) that they're not a problem, but if you have any doubts, place a parallel in your vise before dialing in the fixed jaw. The parallel should really be one---something that's hardened and ground, so if the fixed jaw is slightly warped, the clamping pressure will straighten it and load the jaw against the back support. That way the vise will be parallel when in use.

You see that occasionally when running an end mill under heavy load -----there's a harmonic of sorts where the end mill feeds effortlessly, and makes a serious chattering sound, but a low pitched one, sort of a rumble.

It's nice to see you happy with it----there's nothing worse than being stuck on a machine you don't like. Takes all the fun out of your projects.

Harold

Reply to
Harold and Susan Vordos

Harold,

A good time would be before I inserted it, or better still after I took it out having made good threads ;) Obviously, that's not going to happen. I was able to grind/mill away the burr, and then simply drilled a new set of holes. It was no great loss, but annoying. The choices were to live with the blemish or waste time and metal.

I was doing this by hand, though after a couple of rounds of tapping, I have a better understanding of why the power tools exist.

It'a a clone. What I have been doing is letting a parallel stick up above the jaws, and indicating on it. Are you saying to clamp a "short" parallel, and let the indicator run in the slot between the jaws? I have not tried that yet.

I am also thinking of removing the fixed jaw to run it under a plunge indicator on top of the table. Something almost has to be out of whack given the comparatively steady reading I saw indicating off of the thing that ate the tap. There was some bounce from the flycutter finish, but the needle was otherwise much more steady than I've seen to date.

I will keep that in mind the next time I notice the vibration. I am tempted to say that it happens under no load, but won't swear to it. My best guess has been that it is either a one-phase power and/or slightly inadequate wiring problem, or that I'm not keeping up with the gibs.

There is a slight change in the sound of the machine, but the most obvious symptoms involve the dials. The handles chatter slightly, and the dials will sometimes rotate within backlash. It is intermittent, and I have done some fairly ugly cuts w/o these things happening.

I mention the gibs because I am not completely certain how often to check them, and because I am fairly certain that early on, I missed some slop in the table due to the resistance from the feed. Since I have to remove the feed to lube the table's left port, I try to check the resistance at the same time. My feed is aligned fairly well now, but my most recent order included some import machinist's jacks. I plan to use them to adjust the height while the gears are meshing (unpowered of course), and hopefully get it really right

With that said, I would just as easily believe that I am being tricked by oddities on the power grid. It might not hurt to look at line voltage when it happens, and I should also check for appliances that might be running at the same time.

Bill

Reply to
Bill Schwab

Harold,

A good time would be before I inserted it, or better still after I took it out having made good threads ;) Obviously, that's not going to happen. I was able to grind/mill away the burr, and then simply drilled a new set of holes. It was no great loss, but annoying. The choices were to live with the blemish or waste time and metal.

I was doing this by hand, though after a couple of rounds of tapping, I have a better understanding of why the power tools exist.

It'a a clone. What I have been doing is letting a parallel stick up above the jaws, and indicating on it. Are you saying to clamp a "short" parallel, and let the indicator run in the slot between the jaws? I have not tried that yet.

I am also thinking of removing the fixed jaw to run it under a plunge indicator on top of the table. Something almost has to be out of whack given the comparatively steady reading I saw indicating off of the thing that ate the tap. There was some bounce from the flycutter finish, but the needle was otherwise much more steady than I've seen to date.

I will keep that in mind the next time I notice the vibration. I am tempted to say that it happens under no load, but won't swear to it. My best guess has been that it is either a one-phase power and/or slightly inadequate wiring problem, or that I'm not keeping up with the gibs.

There is a slight change in the sound of the machine, but the most obvious symptoms involve the dials. The handles chatter slightly, and the dials will sometimes rotate within backlash. It is intermittent, and I have done some fairly ugly cuts w/o these things happening.

I mention the gibs because I am not completely certain how often to check them, and because I am fairly certain that early on, I missed some slop in the table due to the resistance from the feed. Since I have to remove the feed to lube the table's left port, I try to check the resistance at the same time. My feed is aligned fairly well now, but my most recent order included some import machinist's jacks. I plan to use them to adjust the height while the gears are meshing (unpowered of course), and hopefully get it really right

With that said, I would just as easily believe that I am being tricked by oddities on the power grid. It might not hurt to look at line voltage when it happens, and I should also check for appliances that might be running at the same time.

Bill

Reply to
Bill Schwab

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