O/T Flexible Fixturing on a Nickel

[MetalMarvels]

At the moment, I have been attempting to figure out how to increase my parts count on the mill, increase my fixturing flexibility, and do more lights out running. With only one mill and a limited budget, invention has been required. While I really like some of the high-density work holding devices - they are just out of reach right now ($$$).

 

Eventually, I would like to move to a pallet system. That, however, is for the future. I have been playing with some of the lost-cost fixturing options like those offered by Mitee-Bite with some good success. However, true flexibility is still an issue. I have worked out a somewhat flexible system based on the Stevens Plate on my mill, coupled with a variety of sub-plates.

 

Has anyone else worked out some low-cost, but flexible solutions?

[Tim Johnson]

Is your mill a vmc or hmc? Are your repeating your parts or are they one time runs? What quantities are you running?

[crazy^millman]

Drill bushings and precision pins for fixture plates. I have also made my own wedge clamps and cam locks like the mighty bee systems over the years. I take a piece of round stock on a 4 jaw chuck and drill a hole off center for the cam. I then part off the disk at the heights I want. If using a socket head cap screw I take a counterbore and put that in there to use the head like a dowel pin for the spinning action. It helps to turn the head down and use a smaller size counter bore keeps from digging in the material for the spinning motion.

 

I have also made my own tombstone fixtures for 4th axis to run 20 parts a side on a th axis as well as make the 4th axis fiture interchageable to relocate to .0005 when taken them in and out so them machine only has 1 minute of down time verse 1 hour changing out parts. I have also doweld the kurt vise and made my own cam lock soft jaws and tapped the sides of my kurt vices in the past and made quick change stopping systmes to make set-up go quicker. I would also look to a deicated full sub plate then do the system you have and keep everything standard using a standard ready and easily made base at my defualt for all Cam programming kind of like a tmepalte for all your programing to work within.

 

The oder of operations has alot ot do with lights out. To many make the mistke of doing operations for light out and not making complete parts. I would set-up 1 plate with the first operation the next plate with the 2nd operation and so forth. That way you are laways producing done parts verse the operation that can hurt you if you are limited on machines as you are. It does require a little more thought up front but if a rush job comes in you can send sautomers finished good and keep all happy verse only keppinh one or two happy by doing things as operations across a whole machine.

 

In case you where wondering I will use my levels as my control for each operation copying and then putting the parts as I want on each level. I then also create operation groups as well as tool groups to keep things straight in Mastercam again requires a little more work up front but pays off in the long run of a job and keep your business flowing in a better direction in today's on time and quick turn around envoriment.

 

These are just my opinion nothing more nothing less. Have a good day and hope that helps.

[MetalMarvels]

tim,

I am running a smaller VMC (Fadal 3016L) with a Stevens Plate on the bed. Typical quantities are 1 to 30 pieces. A "real" production run for me is 300-500 pieces (just got one - 3rd repeat of this part). I don't do a lot of repeat work on the same part, but do a lot of "similar" work for a few customers (i.e. RF boxes in a variety of rectagular sizes). I might see the same part 1-2 times a year, but I am doing a pretty good job of hanging onto repeat customers.

 

However, I am getting rather tired of chasing 2-3 Kurt vises around the place (not to mention that they are bloody heavy) just to get one finished part off at a time (typical op is front, back, and one or more sides). Putting up a dedicated sub-plate is something that I have done, but I don't have a lot of storage room and that approach doesn't seem to make sense when I rarely repeat a particular part.

 

What I am trying to figure out is a way of using my Stevens Plate along with some tooling blocks that would allow me to make "vises" pretty much anywhere on the Stevens Plate. I was thinking of some sort of slider block with a through slot for bolting to the Stevens Plate. The slider block would have a Mitee-Bite Bulldog clamp incorporated into the surface. This would (I think) let me clamp onto the bottom .100 of various sizes of rectagular blocks and allow me to cut out the shape and mill the inside. It would also be compact enough for me to set up several pieces at once.

 

I just haven't come up with a means to hold onto the part when I flip it over to cut off the back (I can't mar the sides of the machined box). The Kurt vise does a good job - but again, I have limited room.

 

Millman - I agree with trying to get a complete part off with every cycle. I have burnt myself too many times with doing a front, then a back, then a side, then another side, then .... oh crap, this part isn't actually symetrical and I put it in the wrong way ....... and then have to start all over at the beginning just to get one more good part off the mill.

 

The 4th axis tombstone sounds like a good possibility (I do have a 4th with this mill). I will have to ponder that one.

[crazy^millman]

Well I have made myself internal block to go inside of boxes if wanting to hold them in a mightybee type clamp. The spacer as I like to call it keeps you from effecting the side walls of the box and you really only need to make like 4,8,12, or 24 max depending on the quainty and I usally make them out of ABS or something cheap like that. With your block on the table just have a spoilboard to machine on glue them down cut out the shape peel them off the spoilbaord and good to go. Should only take about 3 to 4 mintues ea to make these and you would get an ability to do more than just the 3 that you can the kurt method. I am thinking like 12 to 24 at a time if you do the plates right and the parts are small enough also and with the pins and bushing could be loading 2 plates of 12 at a time while the machine runs then just get so 3 or 4 lead screws or even the 1 turn cam lock and good to go for the holding down force of the fixture. I again am thinking have a standard setup block for each side of the 30 x 16 like (2) 15" x 16" plates and might even look at capture type cam hold that you keep the holding below the surface to get the full table travel you want without anything sticking above the plate. Invert a bolt might be a thing to look at here. I owe that to my fellow memeber can't remember who but a great product a little pricey but not really in the grand sceme of things.

 

 

HTH

[MetalMarvels]

quote:

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Well I have made myself internal block to go inside of boxes if wanting to hold them in a mightybee type clamp.

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GREAT IDEA! Didn't even consider that. It would work very nicely with one of the larger boxes that I have to make (rather odd shaped, but overall dimensions of 17.0 x 5.25 inches). Holding it in multiple Kurts was a pain. And making them out of ABS or Ertalyte would hold down on the "scratches" on the finished surfaces.

 

Thanks for the thoughts!!!

[crazy^millman]

No problem hope it works out for you.

[iowajim62]

Hi Gary,

quote:

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The 4th axis tombstone sounds like a good possibility

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It's a good idea, we have homemade "cubes" that sits between the 4th and tailstock which works very good and gives you lots of cycle time. You could have multiple cubes made and loaded with different work and swing those in and out with a cherrypicker and straps. That way just swap cube time and change parts on the other cube while machine is running. Give ya lots of extra parts with little labor on your part.

[Tim Johnson]

Gary,

 

The tombstone set up for plates works very well for us. We also run quantities of 2 to 30, but we repeat our jobs so making different plate isn't an issue. You could also get 4" clustervises from Kurk or Chick in which you could run up to three sides for a rectangular part. On our vises we use steel soft jaws with a step and holes for pins to use as stops. You can record the locations of the stops used so when you run the jaws with the pins in a previous location you can run a location program through the control to save setup time.

If you decide to make your own tombstone(s), assemble them on a plate set up for your table, and you can load and unload your indexer setup in minutes. you may also want a 3" riser under our indexer/tailstock for clearance.

[MetalMarvels]

I really like some of the Chick or Kurt options, but right now the big problem is $$$. I am building the business and have reached the region where I really have to take advantage of unattended evening hours. Being more creative with fixturing was one method that I identified as having a good return on investment. The money situation dictates that I try to stay inexpensive in the short run. The Chick or Kurt options are anything but inexpensive - cost effective perhaps, but not inexpensive. However, they are a significant possibility in the future.

 

Both the fixure plates and "home-rolled" tombstones sound like good possibilities. Fitting the jaws with pins also sounds like an excellent suggestion.

 

Thanks much for the ideas!!!!

[crazy^millman]

One last thing for the company in a pinch but trying to do these types of things. Look in the paper for your local scrap yard and als ocall other Machine shop and see if they have scrap Aluminum to make your fixtures out of. I got a 12" x 12" by 18" block for a tombstone fixture for about $95 dollars and got soem 8" round by 16" long for like $45 big time saving if I was buying it from the metal company. Just a thought hope it helps.

[MetalMarvels]

And a very good thought it is - I just got a dozen 6-foot lengths of 1 x 2 aluminum bars (with the factory markings still showing) for just a little above scrap value. Absolutely prime material! I can't use it for parts needing certs, but for fixturing - great stuff.