• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.

Rotary table newbie.

140mower

140mower

Don
I am pretty confident that I have the work piece centered on the rotary table, and the table is centered under the spindle, so I think all is good, or is it?
While watching a couple YouTube videos a few days ago the person spent considerable time making keys, so the table could be easily removed and replaced and keep its tram. Why? What difference does it make if your table sits a little bit off from the last time it was mounted? You still have to go through the process of centering the work piece on the table, and the table under the spindle. Am I wrong in thinking I am right? ( My wife would suggest yes):rolleyes:
 
I'm looking forward to the "right" answer also. My guess is that the keys get it real close and likely close enough for many projects and save some time when you still have to go through the steps anyhow to ensure dead nuts accuracy?
 
I think that is supposed to be the idea, but all it really changes (at least to my thinking) is the angle of the handle, as the work spins on the same axis either way. They were very nice fitting, but now they are exposed to Knicks and dings that need to be filed before fitting the table. But, since the provision is there.....
I have quite a bit of thought and work into a project that I am well into and I would hate to bugger it up now. I could use the dividing head, which I am fairly comfortable with, but I have a rotary table too and would like to get a little more comfortable with it as well...
 
Personally I feel more confident to center the RT under the quill with DTI, zero the DRO at that position & then proceed with work mounting. My RF-45 keyway slots were just not reliable enough replicating contact. The RT keys were ground & firmly attached. The RT was about the same position on table. It could be that better mills have better slots. I haven't actually tried with my 935 mill. It also could be that what is accurate enough for one person can exceed tolerance for another person. Chances are you are going to be dialing in the part as a second step anyways, be it in a chuck or part clamped to RT. So I just don't see the keys as a big time saver. Similarly I don't use them on my vise either, but I can see for heavy hogging, (well fitting) keys would add stability.

I've even backed off my previous habit of inserting MT/straight test bar in the RT hole & clamping the 3J chuck down with jaws lightly engaged, lazy man mode. Why? because even the act of clamping can put a bit of torque on the screws & drift the chuck. Once the bar is removed & retested its usually out a thou in some direction. If I don't care about a thou, close enough. If I do, get out the DTI.
 
I don’t see the point of keying it unless you never move it about and want to keep it from rotation. It is pretty quick to align and since the Bridget can move the head in the y axis plus produce angles in the x and y there is no guarantee you are centred except with tramming.
 
Keys on a rotary table would only be used in vertical mode to keep it lined up with the mill table's x axis, like if you were working on a shaft/arbor. Can't think of any other reason.
 
Darren said:
Keys on a rotary table would only be used in vertical mode to keep it lined up with the mill table's x axis, like if you were working on a shaft/arbor. Can't think of any other reason.
Click to expand...
I can see using them in that way, but that's not how it was being used. I feel better now, I starting to wonder if I was missing something.
The critical machining has been done and from here in, accuracy is more cosmetic than anything, but having said that I am looking for a professional looking job from a redneck hack.
 
140mower said:
I can see using them in that way, but that's not how it was being used. I feel better now, I starting to wonder if I was missing something.
The critical machining has been done and from here in, accuracy is more cosmetic than anything, but having said that I am looking for a professional looking job from a redneck hack.
Click to expand...

Yea, if the table is laying on its back in horizontal mode, keys would do nothing as the x and y move, unless CNC or a DRO homing position come into play. You'd still have to center the table under the spindle.

Stefan explains it pretty good here:

 
Last edited:
Darren said:
Yea, if the table is laying on its back in horizontal mode, keys would do nothing as the x and y move, unless CNC or a DRO homing position come into play. You'd still have to center the table under the spindle.

Stefan explains it pretty good here:

Click to expand...
Lol, if I were to put a DRO on this drill mill shaped object, it would more than triple it's value....... I just pulled the trigger on a coaxial indicator, should make centering things easier.
 
Well, I am rather pleased with myself, not 100% error free, but nothing critical...
The plan here is to convert my old Ford from stud centric hubs to center pilot style, so I can fit newer rims.... They started out as a piece of rusty 3/4" plate that was found sticking out of the ground in one of our gravel pits. Funny the things a guy drags home......
20220311_141008.jpg
20220322_172648.jpg
 
Still have to drill for the bigger studs, but don't have a 16.5mm, so we'll see what tomorrow brings. Pretty sure I will have to order one, as not much here for industrial supplies.
 
I thought about that, but I don't have a boring bar that small, and it's 32 holes, so I will try and source a drill bit first. Failing that I will try and grind up a cutter of some sort. I'm probably a couple weeks away from tearing the truck down and making the swap.
Been fighting with symptoms of long Covid, and work has been kinda crazy for months now, so things are progressing rather slowly. One more week and I am going to try semi retirement on for size and see how that goes. :cool:
Darren said:
drill to 9/16", maybe 5/8" and use a boring head with a small bar to 16.5mm?
Click to expand...
 
You must log in or register to reply here.
Back
Top