How Easily Does Your Vise Move

You aren't shifting the vise on the table, you are shifting the whole table. Try putting the indicator on something else on the table while you give the vise a whack.

I'm wondering if your clamps may have the threads bottoming out so not providing the full clamp load to the vice, I've seen it before. I once did a job with the vice clamp bolts done up finger tight as I had forgotten to use the spanner to fully tighten them, it did eventually shift but I did a surprising amount of work before it did.

It can be interesting and informative to read the vise with an indicator in the spindle while tugging on the machine in various ways with a strong spring scale. A 50 Lb fishing scale is enough to affect my half century old Clausing. I've been positioning the vise near the table ends where there is less dovetail wear and freeplay than in the middle.

South Bend specifies 0.0007" to 0.001" vertical spindle deflection at "about" 75 Lbs for the plain bearings adjusted with shim packs. That doesn't equate to inaccuracy because the cutting force is nearly orthogonal to the diameter of the part.

The drawing shows one hand lifting a lever of round stock in the spindle bore.

On 9/11/2019 6:30 PM, Robert Nichols wrote:> On 9/11/19 5:11 PM, Bob La Londe wrote: >> The point is even clamped down as hard as I dare the vises still can >> move with only a modestly firm tap with a hammer. Its only a few >> tenths to a couple thou depending on the blow, but it does move. I >> know a hammer blow delivers a deceptively large amount of force, but >> still. It made me wonder how easily those vises really move, and if >> there was something I could do or even needed to do to more firmly >> affix them in place. I tend to mount a vise or in this case two vises >> and only remove them if I have to. Often even temporary fixture >> plates are just mounted in the vises. The two I just remounted on the >> table were last off the machine over a year ago. I've cut a lot of >> parts in those vises. Maybe hundreds. >>

That's likely part of it atleast. Remember I was going back and forth between two vises and adjusting as I went. I was aware I might have lost a step or two, but the steppers were at full power. I was not doing it with the machine powered down. I suspect I could move the table by hand (maybe straining myself a little) if it was powered down.

They certainly didn't bottom out in the table, but I suppose they could be close in the nut(s). I'll see if I can get a hook tool in there to see how deep the ends of the bolts are.

This is an 18 month old machine, although it does have some intended small backlash tolerance. I would sweep the vise jaw, back up and then come into the jaw to zero. Then do the same with the other vise. They might have not read the same each time, but their relative zero should have been the same in relation to each other.

Well, I'm cutting parts on it now. I'll check it again after I run a couple batches of parts that are really non-critical with 360 degree machining.

Maybe I could have been clearer, all the BP 5/8" T nuts I have are tapped so the studs won't go all the way through the T nut, the thread will bottom out in the T nut and not hit the bottom of the slot. I have experienced situations where the nut will hit the end of the thread at the top end of the stud and only minimally clamp the vice or fixture. Worth checking that this isn't happening with your clamping arrangement what ever it is. If not the case must be some other issue but worth checking.

Regarding  slot damage I have only seen that on a badly abused BeaverMill table and then the current owner knew that the previous owner had been using the wrong sized (too small) T slot nuts which resulted in the damage to the underside of the T slot.

I understood. I have 7 mills. 6 currently in operation. I have t-nuts in the slots on all of them. I have also made t-nuts, but when I make them I tap all the way through. Its a lot easier to make sure you won't bottom out in the table before hand than it is to make sure you won't bottom out in a t-nut.

Ok one of them doesn't really count. Its a mill drill that doesn't even have a fine feed, but it does have a vise bolted to the table. 5 real mills in operation. LOL.

I have a fairly decent stock of heavy washers, and have made a fair number of spacers so I could use the bolt i have handy instead of spending all day looking for one or going to the store. Even when I don't need one for length I try to use atleast one because it acts like a thrust bearing and the vise moves less when I torque it down. It also spreads the load from the bolt a little, so a bolt head is less likely to damage a cast fixture, angle plate, vise, etc.

One set of six parts cut so far, and the vises have not moved. Maybe I was just being paranoid.

Instead of a sheet of paper, a bit of valve grinding or lapping compound works great to get some extra grip between clamped surfaces, and it certainly isn't going to wick anything water soluble.

I used to do this often (>10 times / year) in my motorcycle mechanic days. It was all too common that people would replace shear keys with hard keys to hold the flywheels on the crankshaft. Next time they banged it into gear, the key, instead of shearing, would mangle the tapered end of the crankshaft under the momentum of the flywheel. We'd just grind off the burs, lap the flywheel to the crank, clean it up and apply some fresh compound to the taper and bolt it up with no key. NEVER had one of those slip after that repair.

Now I feel inadequate as I only have 3 lathes and 2 mills but they pay their way and always useful, the small CNC mill is a work in progress. A mate down in Cornwall mentioned recently he met a guy down at the local mine with 30 lathes, then largest being 12' diameter capacity and a 30' bed, I guess he has the need, space, and connection to the national grid.

Snort! Well know you know why your lights dim and flicker at times ;-)

What?! No green LocTite? Sorry. That's my stock fix for that bushing that goes behind the clutch basket for a Harley clutch to ride in the seal in the rear primary. Got to heat it to get it off, but unless you have major tranny problems how often are you going to pull that shaft anyway.

Lapping compound. That is certainly an option I had not considered.

On 9/13/2019 11:00 AM, David Billington wrote: > On 13/09/2019 15:49, Bob La Londe wrote: >> On 9/12/2019 3:15 PM, David Billington wrote: >>> On 12/09/2019 22:51, Bob La Londe wrote: >>>> On 9/12/2019 4:33 AM, David Billington wrote: >>>>> On 11/09/2019 23:11, Bob La Londe wrote: >>>>>> On one of my machines I pulled of the pair of lock down vises I normally have on the table so I could mount some custom fixtures to machine a mold that was almost the full work envelope of the machine. >>>>>>

I often struggle to keep them all going. I just can't do CAD/CAM work fast enough. But there are days when I have them all going and realize I need to do something else, and just have to wait. Except for the mill/drill all my mills are CNC. That being said I've made parts in a pinch in a hurry on the mill/drill too. LOL.

I'd love to have a CNC lathe, but the cost for something decent always makes me think twice. Also the electrical budget in my shop is very tight. Not money, but amps. I just have a single phase 100 amp sub panel feeding the whole shop. I often find myself adding up what's running in my head and guesstimating how close I might be to tripping the main if I start just one more machine. Its one reason I am the only one with a remote for the overhead doors. LOL. I do have three lathes, but only 2 in operation. Well not counting my wood lathe. It works, but I only use it once or twice a month. So I guess I have 4 lathes. Now shall I start counting badsaws and drill presses. LOL. I found duplicate equipment saves me a lot of time for jobs that are done repetitively and repeatedly. One lathe is set to do just one job. Radius the end of dowel pins. 2 drill presses are dedicated to automatic tapping heads, etc etc...

As a one man shop an idle machine still saves me time when I need it if its dedicated and always setup for a particular job I do routinely. I've debated a gang drill press table so I can pass certain jobs down the line, but they are expensive. Even used they cost a bit. I might make one out of cheaper drill presses sometime... if I ever have the time.

Oh, great. Another project to put on the long list. LOL

Actually I have considered another idea. We get a LOT of sun here. I could easily put 20KW (maybe 30) of solar on the roof of my shop to supplement the available electrical budget during the day time. I do work into the evening, but usually only have or one two machines running as I am finishing up things before dinner. Then I could even air condition the shop instead of just the office. All it takes is money.

Next time I have my Taig mill apart, I plan to use some lapping compound to help secure the Z column.

That one is easy, power it with 120VAC and clip the CT around one input leg to just read the current.

Well, I do have a 120V outlet next to the panel, but the panel is on the outside of the building, and the sun here is absolutely brutal. There is a reason there are materials tests sites out here in the desert.