Trying to automate doing up fixture bolts using my VMC...

[3Dmech]

Hi All,

I’ve got a repeat job on my Brother TC-S2B that involves loading 200 Aluminium/Rubber bushes onto a fixture I made and then securing each bush through the centre with an M5x20 hex bolt. At the moment I use a cordless drill with adjustable toque, fitted with a hex key to do these 200 bolts up, and then undo them afterwards (tedious!!) after 1800 holes have been drilled.

So, I’d like to automate on the machine this tightening and then undoing. I still plan to load by hand every bolt into position (and then remove afterwards once undone). My thoughts are some sort of attachment that I can put in one of my BT30 collet chucks that:

1) Has adjustable torque (just like my cordless drill)
and
2) is spring loaded (so that I don’t need to worry about Z-axis position when the bolt is being tightened or loosened).

I was half tempted to rip my old drill apart and make something up with the chuck, but ideally I’m hoping there might be something already on the market….. any thoughts?

p.s… I’ve never used a tapping chuck (as always rigid tap) but I’m guessing it’s spring loaded (but doesn’t have adjustable torque).

Thanks.

 

[GiroDyno]

Floating tap holder and a fix-it-stick. They're fixed torque but cheap so you can get a few different spec if needed.
Those tap holders don't have a lot of travel so you might end up needing to add some z motion while tightening to keep it preloaded depending on the pitch and how long your screw is.

Do you have a second fixture you load up outside the machine while its cutting on the first?

 

[dandrummerman21]

Some floating holders have more travel. We have a lot of lyndex floating holders with bilz style connectors that have maybe 1/2" of travel both tension and compression.

After you remove the screws with the spindle, change tools to a magnet to pick all the screws up!

 

[DDoug]

How about a stud, swing washer & nut ?
You just need to loosen 1 turn or so.

 

[Scruffy887]

Fixture needs to be an interchangeable pallet. Use a straight air powered screw driver with adjustable torque settings. Hang it on a balancer arm.
Load and unload while drilling another.

 

[corednc]

Floating tap holder is the ticket. See this video for an actual implementation. He uses the torque sensing in a Haas spindle but I believe a Brother would have something similar. Skip to the 2 minute mark.

 

[3Dmech]

Hi!
Thanks for all the comments and advice. The real sensible option is to make another fixture that I can interchange as suggested, the thing is, I like the time it takes to do the cycle (well over an hour) as it gives me time to do other stuff..... means the job on the machine takes longer than it could though I know.

 

[3Dmech]

How about a stud, swing washer & nut ?
You just need to loosen 1 turn or so.

Nice idea, but sadly the swing washer would cover one or two of the holes that need drilling.

 

[3Dmech]

Floating tap holder is the ticket. See this video for an actual implementation. He uses the torque sensing in a Haas spindle but I believe a Brother would have something similar. Skip to the 2 minute mark.

Thanks - I'll take a look ref torque sensing on my Brother.... will be great if it does.

 

[gkoenig]

I might try an expanding collet instead of a screw. MiteeBite makes one that can be milled down to just under 5.5mm, so you are close to the clearance hole size for the M5 bolt. #31730 from them.

Tightening and loosening the expanding collet fastener will be way faster than fiddling with a bolt.

 

[gkoenig]

Thanks - I'll take a look ref torque sensing on my Brother.... will be great if it does.

Brother only introduced spindle load monitoring with the Speedio X2 variants a few years ago.

 

[DDoug]

Nice idea, but sadly the swing washer would cover one or two of the holes that need drilling.

Make a custom swing washer with those holes already in them.

 

[Milling man]

I’ve never used a tapping chuck (as always rigid tap) but I’m guessing it’s spring loaded (but doesn’t have adjustable torque).

This is exactly what you need. Just a tap chuck with torque limit and axial compensation, average quality.
There is one non-obvious problem with any automation - any, even the most insignificant trifle, turns into a huge problem! We do not even think about how difficult it would be to program the work that we do every day for a robot.
The screw began to screw into the hole a little crooked - we just unscrew it back and try again. How does a robot (or a machine, it doesn't matter) understand that something is going wrong? How will the robot understand what to do with this "something goes wrong"?

 

[CMJ1970]

Make a custom swing washer with those holes already in them.

Yup, fair enough! Stupid me for not thinking that.... still sadly not an option with current fixture as all bushes are nearly touching each other and no room to anchor these swinging washers... maybe an idea for something in the future though thanks.

 

[CMJ1970]

This is exactly what you need. Just a tap chuck with torque limit and axial compensation, average quality.
There is one non-obvious problem with any automation - any, even the most insignificant trifle, turns into a huge problem! We do not even think about how difficult it would be to program the work that we do every day for a robot.
The screw began to screw into the hole a little crooked - we just unscrew it back and try again. How does a robot (or a machine, it doesn't matter) understand that something is going wrong? How will the robot understand what to do with this "something goes wrong"?

Yeah good point.... by hand I normally have to correct at least a couple of them when loading it. Normally because my cordless drill is maybe not dead perpendicular to the table though.... at least if machine was doing it, it would be... but regardless as said good point as something can always go wrong in the hands of automation.

 

[CMJ1970]

Brother only introduced spindle load monitoring with the Speedio X2 variants a few years ago.

Ah that's a shame.... had a look through my programming manual and couldn't find anything.

 

[3Dmech]

oops I've got 2 user ID's for some reason (one on my 'phone and one on PC).... '3Dmech' and 'chrismjones/CMJ1970' ... I'll use 3Dmech going forward. Sorry for any confusion!

 

[Pattnmaker]

Not sure if you volumes justify this but what about re making the fixture so all would clamp at once. Use the mitee bite id clamps gkoenig mentioned screw them into a plate like an ejector plate underneath your fixture die springs holding the clamps closed. A single fine thread machine screw in the middle of the ejector plate to release all the parts. Depending on size or pressure needed maybe 4 ejector plates 4 screws still beats 100.

 

[guythatbrews]

It really helps to turn a minor diameter pilot on the end of screws and studs one diameter or so long. A great help with quick assembly.

 

[Milling man]

by hand I normally have to correct at least a couple of them when loading it.

I don't know, how many parts you need to process, but maybe think about ZeroPoint systems, or something like this. As Pattnmaker rightly pointed out, you may not need 100 attachment points, but much less. These systems are designed for automation, unlike bolts