Semi-automatic parts weighing/counting machine.

[JimDawson]

I have been asked to build semi-automatic parts weighing/counting machine for a customer. We decided to make it rotary to save space, and have a two tier rotor system, top to store bulk parts, bottom to store kitted parts. An operator will select the order on the computer screen and physically move the parts from the bulk bin into the weighing/counting hopper, then release the parts into the kitting bin. Each time the parts are released, the bulk parts (top) rotor will rotate to the next part in the kit. When the kit is complete, the lower bin will index to the next station and the process begins again. From this machine, the kitted parts will go to the existing bagging/printer for final packaging.

A concept overview, just to put this in perspective, the lower rotor is 28'' diameter. The numbers and letters will correspond to part locations that will be programmed into the system.


So how do you do the machine work on a 28'' diameter ring when your machine only has 14'' of Y axis travel? Drilling mount holes, milling bin pockets, engraving letters & numbers, accurately machining the ring gear pocket.

Time to dust off the rotary table.

Some time ago I converted my 6 inch Vertex Super Spacer to a rotary (4th) axis for another project. See that project here: https://www.hobby-machinist.com/threads/4th-axis-build.40642/#post-348948



I need to mount a table on it in place of the chuck. So this is the 12 inch table that will bolt on in place of the chuck. This will be made from 3/4 inch MIC6 aluminum tooling plate. I need to dig that out in the morning, need to move some stuff around in the shop to get to it with the forklift.


But I have a little clearance problem, it was designed to take a 6 inch table, but I want to use a 12 inch table to better support my 28 inch rings. The mounting foot sticks up about 1.25 inches above the mounting surface.


I had a couple of options, build a riser to put the table above the mounting foot, or simply trim the mounting foot. After some thought and testing some alternate clamping methods, I decided to trim the foot. It won't affect the horizontal operation, and I can still properly clamp the unit to the table. Tape over the various holes to keep the cast iron chips out of the works.

1/2'' roughing end mill, 0.600 DOC, 120 FPM (900 RPM), 0.375 stepover, 7 IPM feed.



So for the moment, the next order of business is to rough out the rounds. Two 28 inch, one for the lower rotor and one for the spoil board, and one 27 inch for the upper rotor.

First I had to make a trammel point to be able to swing the circle with a Sharpie. Some 1/4'' SS rod, and a couple of other small scraps and a few minutes on the lathe and presto..... instant (almost) Sharpie trammel point. The Sharpie is a light press fit into its holder.


And we have a circle. The large parts of this project are made from 3/4 MDF. Nice stuff to work with. The local lumber supply has a panel saw, so I had them slice the two full sheets of MDF into my rough sizes, $0.50 / cut and worth every penny so I didn't have to handle full sheets.


Then over to the band saw for roughing out the circle.


And 3 rounds cut


This is how they will fit on the mill, had to move the ram out a bit from its normal position. This gives me a Y work envelope that is about 6 inches wide, plenty of room.


That's all for tonight folks, stay tuned for more.....
.

 

[brino]

Excellent!

I am really in the mood for one of your big detailed builds.....really looking forward to this.

Thanks for sharing this Jim!
-brino

 

[JimDawson]

Well I was going to make the new rotary table out of 3/4 aluminum tooling plate, but......... I was ordering some other parts for this project from McMaster and on a whim decided to look at their offering of cast iron which would make a much better table. Hmmm, only $89 for a 12x1'' round. OK, that is a fair price. Got it this afternoon.



It's advertised as oversize, it turned out to be about 12.5x1.3 Nice! It was rough saw cut, but they must have a pretty good saw, the two sides were parallel within about 0.005'' I was impressed.


So find the center by scribing several lines using my V adapter.


Then over to the mill to 0 on the center T-slot, for this I use a 1/2'' cap screw in the drill chuck. This gets me close enough to be able to drill through the work into the T-slot.



Then stage a T-nut at the 0. Now when I drill through I'll have the T-nut directly under the hole and can screw the hold down screw right in without having to try to re-zero the part.



Then move the part center under my center point in the chuck. Drill and bolt everything down.


So first face it off. Bolted down with a piece of 3/4'' MDF under. I'll be drilling some through holes later, thus the MDF.


And done about 25 minutes later. 0.020'' DOC, 0.400'' step over, 14 IPM, 150 FPM cutting speed (1140 RPM), 1/2'' 4 flute HSS endmill.



So next is to make a pocket to fit the register on the RT (see RT above)
0.160'' DOC, the rest of the cutting parameters are as above.


Found an odd glitch in my software and this is as far as I got today. More tomorrow.

The software glitch turned out to be an odd couple of lines in the G code. Never seen that before and caused my software to get confused. I wrote a couple of lines in my code to take care of that problem. This must have come from an updated post processor in Fusion, as I said, I had never seen that before in the G code. Just a ''S1140'' (spindle speed) on a single line by itself. Normal format for spindle speed is S1140 M3. Never seen it without the M3 or M4 before.

 

[Boswell]

Great Idea to stage the T-Nut below the how you are about to drill so you don't have to move the part.

 

[JimDawson]

Got a little more done today.

Finished the register pocket


Then turned it into swiss cheese. There are 3 mounting holes drilled 0.390 through, and 36 3/8-16 tapped holes for securing work to the plate. The power tapping had a high pucker factor, to get through the plate it took all of the tap so running it down until the last thread of the tap was at the top of the hole before hitting reverse. I ran it pretty slow. There was no way I was going to hand tap all of those holes.


So tomorrow I'll flip it over, mount it on the RT and finish the other side. Then I can set up to work on the big MDF rounds.

 

[JimDawson]

I finally got back to this project after the bit of weather we had. Finished up the new tooling plate, didn't get any pictures of that. Got the spoil board mounted up and it is time to actually start making parts.

This is the lower rotor, the pockets fit these plastic boxes. 20 of them on the lower rotor. Pocket, rotate 18 degrees, rinse, repeat.


A wider view


Engraving the numbers, 0.025'' deep. Took longer to program this than it did to cut it.


And rough cut out the center for the drive belt pocket.


Still a little small, on purpose. I didn't know the exact diameter of the belt so had to sneak up on it at 0.003'' per pass until I got it to fit.



Cut, test, cut, test, about 9 passes to get to here. And about 1 hour later, it fits.



Then take another cut to accommodate the carpet tape I'm going to use to hold the belt in place. The tape is 0.005'' thick so one more cut. The real problem with working with an organic material (MDF) is that it will most likely change size as the humidity and temperature changes and that belt needs to be a pretty tight fit and it won't change size. Hope this doesn't come back to bite me later.



So tomorrow I'll figure out where the screw holes need to go for the lazy susan bearing. I think I have a good drawing of it, but I need to confirm. https://www.amazon.com/TamBee-Heavy...Lazy+Susan&qid=1613791293&s=industrial&sr=1-1


Once those mounting holes are done, then the lower rotor is complete. Then on to the upper rotor...... Stay tuned.

 

[JimDawson]

I got the screw holes for the lazy susan bearing measured, that was a bit tricky. I tried a couple of different methods trying to use my DRO and a center point, but I finally just used a tape measure. It worked.



And the top rotor is finished, engraved with letters.


So on to the top drive gear


and done. The belt is more or less a press fit onto the MDF. Did this the same way as the lower belt drive. Cut, test, cut, test..... No way to get a good measurement.


I didn't get this picture of the top of the tooling plate before. Engraved the bolt circle diameters so I don't have to measure next time.


So one more operation before I tear down this setup, clean up the OD of the tooling plate so everything is concentric. I was thinking that I may have screwed up when I cut the center hole. I cut it the same size as the center hole in the RT so I could use it to dial in the center. But it would be nice to have a bolt hole in the center to anchor work on to the table. I'm going to thread mill the first 3/4 inch of the hole 2''-16 and build a plug that will screw in that I can use for an anchor point. I may do this before I tear down the setup.... or not. I may wait until I need it. Didn't feel like doing that today, time for a bowl of soup and a nap. That's the nice thing about being retired, if I don't feel like doing something today, it will just wait until I do feel like it.

So the next piece of the puzzle is the support bearing housing for the upper rotor.



I found this in the scrap auxiliary metal storage bin, it has the correct bore and about the correct OD, going to revisit the design and see if I can save a bit of work.



I hope a pair of of these roller bearings are heavy enough to support the 5 lb upper rotor I chose them for the ID, needs to fit the 2'' center support tube.




More later........

 

[JimDawson]

I finally got started on the prox bracket. This holds the 3 prox sensors on the machine.

And in position



The bracket is 3/4'' thick, but the one inch material looked like it had this part in it, and was on top, so I grabbed that so I didn't have to dig for the 3/4, I'm lazy. So the first thing is remove 1/4 inch over the area of the part.



Pocketing the for weight reduction. (and just the cool factor)


Then cut out the outside. This had a high pucker factor. 3/4'' deep (by 1/8 steps) with a 1/4'' end mill. Full width of cut, and nowhere for the chips to go. Had to stand right there with the air nozzle the keep the chips out of the tool path, even with the mist coolant blowing.


And side 1 done.


The next step is to turn it over and put the lighting pockets in the other side.

So how do you exactly locate an odd shaped part? Stay tuned to find out.

 

[BGHansen]

The next step is to turn it over and put the lighting pockets in the other side.

So how do you exactly locate an odd shaped part? Stay tuned to find out.

Let me guess, knock in some dowel hole for locating pins with your CNC to pick up edges to locate the part, then clamp? Pick up the corner at the bottom right with a dowel pin on the horizontal and vertical, and a third pin to pick up the face on the surface at the upper left? I'm on pins and needles! Not literally, but I'm always looking for clear ways to secure and locate oddball parts.

Bruce

 

[Boswell]

my guess is that you have what looks like a 90deg corner at the bottom (last picture). Seems you could locate X and Y from those two faces.