Here's You Sign #98 - Pennsylvania USA

[pblackburn]

Working on emblem for my machinist. Here is a test cut. Have some rework to do before laying out for the cabinet door. 4th axis design under way. Finally changed my slave axis to B instead of A. Looking at using the 2nd parallel port pins 2-9 that are not being utilized on my PMDX-126 breakout board. I only need 2 for the step and direction.

[pblackburn]

About have the design complete for the 4th axis. Still need to find a suitable tailstock to work with my layout. 6" Chuck arrived today.

[pblackburn]

MERRY CHRISTMAS EVERYONE and safe holiday

[Alan_c]

Thanks Pete and here's wishing you and your family a Blessed Christmas.

[domino11]

Thanks Pete! Hope you and your family have a Great Christmas as well!

[pblackburn]

YouTube Video
Cutting out the emblem above

[pblackburn]

Another PhotoVCarve


P1020116 by Pete-N-Faye, on Flickr

[pblackburn]

Finally have cabinet doors and final layout from the machinist. Cutting now, pictures later.

[pblackburn]

Door 1 Cut, on Flickr


Door On Table, on Flickr


Door 2 another view, on Flickr


Together, on Flickr

[darren salyer]

Thats pretty cool, Pete.
In the seond pic, what is bolted to your crossbearer, to the right of your spoilboard?

[domino11]

That looks like a Z Zero plate.
Sorta like This One

[nsfr1206]

Alabama fan?

[pblackburn]

Darren,
Heath is correct. It is a Z zero plate. It is a digital probe I got off of Arnold Minear. I read a post here back a while ago. It comes with a plate the goes on in place of the probe. Used in conjunction with the Mach Blue Probing by Big-Tex Screenset and you set your calculated Z offset. The way it works is after you make a tool change you click on Tool Change Zero Setup button and it will touch off the probe twice and set the value to the Calculated Z Offset value you have entered in the textbox and then automatically start the next toolpath. That way I always have an accurate way to resume. It is within a couple thousands for repeatability. I have never cut into my spoil board. I have done V cutouts as well as flat. I have started jobs and shutdown for two days and resumed. This was the most feasible for me.

I had to take a lot of extra steps to make this machine worked well for me. Easily moveable (complete bolt together) for moving to its future home, hardened bolt-on v-rails (RC58) and (RC45) rollers for better surface running and preventive maintenance, but the dust collection I spent the most time on. I needed it to be as dust free as possible because of its location. Since MDF is very dusty to cut I wanted no way for the dust to escape the shoe. I do not need to vacuum after running for 8 hours to give you an idea. The touch off plate was a big bonus and helped this issue but so did the water cooled spindle.

[pblackburn]

David,
Yes, my machinist is a Alabama fan. I told him for all the work he has done for me they were free. Understand he doesn't charge me for the work he does so it was the least I could do.

[pblackburn]

Working on changing over the remaining 3 gearbox axes and finishing final machine on the 4th axis build. Have received all the quotes for the custom timing pulley I want. Have request for quotes out for the laser cut parts I need for the retrofit of the remaining axes.

[pblackburn]

Laser parts ordered, custom tooth timing gears ordered, worked out how to re-use the steppers off the gearboxes. 6 weeks until the changeover. About finished with the 4th axis assembly for the chuck. Only waiting on pulleys, motor and drive (spring project). Now I am working on removing sag from my main beams in my house. All projects on hold for a while until I fix this problem.

[domino11]

I am interested to see how you reuse the steppers. I thought there was
something that did not allow you to do that. Cannot remember what it was,
but something about how the gearbox was attached to the output shaft?

[pblackburn]

Heath,
The steppers have a spline shaft that is 0.400". It has a diametrical pitch that I have not been able to identify with 14 splines. Working in maintenance, I have the advantage of working with many technicians that have worked in vast backgrounds. After picking all the available brain power at my disposal we came up with the following, using a 18 tooth timing pulley, bore out the hub end to 0.400" by 0.250" deep and then bore the rest at 0.030" over the smallest measurable diameter from inside the splines. On this shaft it was 0.320 so we bored to 0.355". I then turned down a 3" piece of round stock to have a stub on it that was 0.625" round with the length of the stub 0.500". In the center of the stub, I left an alignment point to be received by the bell end of the stepper shaft so I can press the hub onto the shaft. I carefully removed the sticker on the back side of the stepper to expose the hole to the shaft of the stepper. Using an arbor press, I set the stepper on the 3" round with the aligning stub and then pressed the hub onto the shaft. It worked just as the one tech said it would. The hardness of the shaft would peel the aluminum of the hub away as it pressed. To give you an idea, the arbor has a 30" handle and the last 0.25" of press movement I was hanging all my weight on the handle. I chose to use the arbor rather than a hydraulic press because the arbor has a better alignment properties than being hydraulically pressed plus you can feel the resistance and make an adjustment if required. This left small voids that I could then fill with Loctite 680 retaining compound. If you have never pressed off an item that was retained with Loctite 680, you do not have an appreciation for the compound. We use it for retaining gears and bearings on mechanical presses. It can either be compromised with a torch or a hydraulic press. I have seen 6307 bearings require more than 20 tons to break the bonding surface. Other chemicals can loosen the surface tension but I will have to cut the pulley off later when it will need replaced. After the compound had cured I tightened the set screws on to the shaft. I had to allow on the mounting plate the diameter of the pulley to be able to pass through the plate since the pulley is pressed and locked on the shaft.

[pblackburn]

Heath,
I forgot to mention that the 6307 bearings are only retained with this when the surface has been wore and is no longer a press fit. We use it on a 500 pound flywheel. So the torque retention of the compound's surface strength is extremely impressive.

[pblackburn]

A little more information about the upgrading. Since I am re-using the steppers off the PK296A2A-SG7.2, the custom timing pulley is a 130 tooth pulley. I am using an 18 tooth on the stepper to maintain the 7.2222 ratio. The assumption is the stepper is only 97 oz-in because the rated holding torque is 704 oz-in. The frame size of the stepper (3.54") is different also than the PK296-F4.5A (3.35") so the you can not use a universal design between the two. I had to modify the Y car in order to mount the reduction assembly. I made an angle bracket to mount the control station on the top of the Y-car so I could trim the metal away for clearance. The movement per step is still 3/10 of a thousandth which is more accurate than needed for wood. I am using the same profile idlers as before but this time out of Delrin. I have to get the timing pulleys anodized after I receive them. There is a company close that will do them, fortunately I am well under the minimum charge however I wish I had more aluminum I needed hard coat anodized. I had all the manufacturers quote unfinished and anodized and the cost per anodized for one pulley was more than I can get all three plus done from the anodizing company I contacted. The best quote I received for the pulleys was from SDP but it required a minimum of 10 for $79 each. I went with the next best for $123 each. If I had a milling machine with a 4th axis controlled by mach I could have saved $70 per pulley but I don't so I went with the next best thing. I will post pictures of the assembly as I start the process.

[domino11]

Pete,
Sounds very interesting. Looking forward to the pics!

[sailfl]

Pete

When you remove the gear box from the PK296A motors, would you take some pictures of the end of the motor and the gear box.

What is it going to cost to make the belt drives / motor?

Thanks

[pblackburn]

I will try to do that tonight. The one I have already apart has the timing pulley on it already. The cost is about $175.00 per axis. Would have been an extra $140 if I would have to by the stepper. $21 for laser cut steel parts, $125 for 130 tooth gear, $20 in other steel parts. I have no costs for machining so I cannot answer that. The biggest savings will be the time saved after the parts are cut. Now I have a lot of time in blending the unmatched start and stop points where the cutter was.

[pblackburn]

PK296A2A Stepper, on Flickr


PK296A2A Gearbox, on Flickr

[pblackburn]

Nothing worse than waiting! 4 weeks left

[pblackburn]

Some updated pictures

This is the template I used to check for clearances of the new design

Template for 7.2 Belt Reduction, on Flickr


This is the modification I had to make to the Y-Car for the clearance of the new belt reduction drive. Moved the control box to new location on top of the Y-car and trimmed off the metal originally for mounting it.


Modifications, on Flickr

[pblackburn]

Laser cut plates arrived, some machining required for relief for stepper. Posts need welded and aligned, bearing cups need welded on. And lastly painted.


7:1 Laser cut plates, on Flickr

[Fox]

Big Boys ! I reckon the 7:1 is due to the originally geared engines ?

[pblackburn]

Yes, it is actually 7.22:1. My fingers were lazy. I am using the original steppers from the gear drive which would require the higher ratio to achieve the right amount of torque.

[pblackburn]

The stepper with the pulley pressed on using arbor press and Loctite 680 applied.

Stepper of PK296A2ASG7.2, on Flickr

Idlers I will be using. Need 2 for each of the three axes

Idler , on Flickr

Drive shaft. Will hold the 130 tooth timing pulley and pinion for the rack. Not finished yet as it can not be fully sized until the timing pulleys arrive. I also have to trim off the end once I know the length to fully engage the pinion. Need to mill flats for the set screws.

Drive Shaft, on Flickr

Side view of the assembly, posts welded on back plate and top plate is screwed down from the top.

Side view, on Flickr

Top view shows the relief cut in for the stepper and bolted together.

Top View, on Flickr