PATRIOT Y AXIS MODIFICATION

[smallblock]

On my old Shoptask, the X handle was on the right end of the machine and the Y handle was on the front of the table. The Patriot is just the opposite, so I felt like a guy driving a right hand drive car. JT explained to me that in order for the Y handle to be on the front of the machine, it would protrude about 7" out and make the crate bigger. As it is now, he said they can get 22 machines in a container packed like sardines- 1" taller, wider or longer on the crate would mean only 1/2 the machines in the container, raising the cost by about 150.00 per machine. He said they tested a handle with a long center boss, but it was too flexible and the dial became hidden under the table when it was fully retracted. What was needed was an easily removed and installed bracket to hold the handle and dial so that it could be packed seperately and bolted on by the customer after the crate was opened. JT offerred to supply any parts necessary if I could devise a solution.
After rolling the idea around in my head for a few days I concluded that the only solution was to create an assembly complete with handle, dial and bracket that could be attached to the machine by the customer in a couple of minutes. After looking over the stock assembly and making some measurements I decided that I could make a bracket that would attach to the existing Y lead screw bracket and use the existing bolts, since this bracket is aligned and dowelled at the factory, removing and replacing the bolts would not create any alignment issue. There is enough room for an additionbal 1.25" slot to be cut into the shield so that the new assembly can be bolted up without removing any parts. I felt that the simplest attachment would be to have a flat on the end of the Y axis lead screw and a hole in the new handle shaft with a set screw, so when the new bracket was bolted in place, you would simply tighten the set screw onto the lead screw and have a positive connection. For any one thinking of making this upgrade, here is how it went;
1. I needed an extra 1" length on the Y axis screw for the stub with a milled flat. To do that, I needed to remove the screw and turn it back by 1" and then re-mill the keyway for the helical gear. The screw is long enough to do this without loss of any table travel.
2. I removed the CNC motor bracket and drive pulley from the back of the table and just cranked the table until it came clear of the nuts and then slid it back a few more inches.
3. I removed the self locking nut from the front end and pulled the lead screw out the back. I removed the helical gear and key and got ready to turn the shaft- OOPS!- A flash of panic when I realized I had no Y axis screw to do the turning. After a moment it came to me to use my compound- I slid the Y table back to the center of the carriage and locked it down and positioned my toolpost so that I could use the compound slide for the turning.
4. Now it was time to re-cut the key slot for the helical gear- same issue, no Y axis travel, so I set my mill vise up to hold the shaft in line with the spindle and just tapped the Y table with a rubber mallet to get it centered and cut the slot with the 3/16 end mill that came with the machine- 2 passes brought it to the 5MM width of the factory key.
5. The extra 1" end of the shaft was turned to 10MM and I used a 12mm die to re-cut the threads for the self locking nut.
6. I replaced the screw and now had the 1" end with flat protruding from the bracket.
7. Because the maximum size of the slot in the shield was 1.25", I decided to make the new bracket assembly that size. I found a piece of 1.25" DOM tubing and saw cut a piece of 1/2" flat stock to the right dimensions.
8. I layed out the distances for the 2 bolts and the lead screw hole on the flat stock and drilled the bolt holes to 8MM and then counterbored them about 1/2 the thickness of the stock. The center hole for the lead screw was drilled to 1/4" so I could use a hole saw with 1/4" pilot.
9. I bored the plate with a 1 3/6" hole saw and then measured the actual size after I was finished. On my DOM tubing I turned the end back 1/4" to the size of the hole in the plate with just enough difference for a press fit. I pressed the tube into the bracket and and tack welded it.
10. On the other end of this assembly where the handle fits, I needed a round part the same diameter as the dial for the thrust bearings to fit against and for the dial reference mark. The dial turns out to be 50MM, which is just under 2". I found some 2" solid stock and saw cut a piece.
11. I faced off one side of the 2" stock and then turned a boss protruding out by 1/2" with the OD to be a press fit inside the DOM tubing. I then turned the piece around and turned the other face and turned the OD to 50MM ( this is where the DRO is nice, switching from inch to metric).
12. Next I drilled the part to 14MM which is the size of the original shaft and thrust bearings. I pressed the round part into the DOM tubing and now had my bracket with bolt up flange on one end and dial boss on the other.
13. A quick bolt up confirmed that it all fit OK, and I made my measurements for the new handle shaft.
14. The shaft was made from a piece of 3/4 solid stock- one end was turned to 14MM and a 5mm keyway was cut for the handle and dial collar and the end was threaded to 10MM for the self locking nut. The other end was drilled to 10mm to fit over the end of the Y axis lead screw and drilled and tapped for a 5mm set screw.
15. I then milled a flat on the DOM and drilled a hole for access to the set screw.
On my first fit up, it worked great- just remove the 2 allen bolts in the Y bracket, slip the new assembly over the end of the shaft, replace the allen bolts and tighten the set screw. The whole thing was very solid and the handle turned the table smooth as glass except for another OOPS!- The machine is designed so that when you turn the Y handle clockwise, the table travels toward the chuck- when you bypass the helical gears and turn the screw directly, the tables moves in the other direction- what is needed is a left hand lead screw. Its funny how it never occurred to me during this whole process. However, JT said he has a lot of LH lead screws and nuts left over from ball screw conversions and he is sending me one, so I only need to go through the first step again.
The final step was cutting the slot in the stainless steel shield- I ran the carriage all the way right and left and made note of the end position and marked the shield. Then at each end I used a 1.25 " hole saw and bored a hole. From these holes I marked a line and used a jig saw to cut the slot.
One thing I noticed was that the specs for the Patriot give you 10" X 23" for the travel, but on my machine it is 11" X 25", so its a bit of a bonus.

[smallblock]

I got the left hand screw and nuts yesterday from JT- This weekend I plan to machine the new Y axis screw- will post the results when done.

[smallblock]

Just an update on my handle project. I machined the new LH screw and installed it with no problems. My cross table now moves in the proper direction and I find the location of the X and Y to be pretty comfortable in the "traditional" locations. Only one more thing to do- have to re-mark the power feed direction sticker since that is now reversed. I am including a picture of the 2 screws and also a picture of the adjustable nut. You can see the 2 small set screws used for the backlash adjustment. The bracket that holds the 2 nuts is divided into 2 parts so you can clamp the round nut tight and leave the flanged nut loose. Then by turning the set screws in against the bracket the flanged nut is forced away from the round one. This puts contact on both sides of the lead screw. Be real easy on this adjustment cause it only takes a small amount of adjustment to get you down to zero lash or even to the point of binding the screws. Zero lash is possible, but at that point you can really feel the added resistance in the handle. I found that between 0.001 and 0.002" you still have an easy feel when turning the handles. CNC guys could probably go tighter depending on the power of the drive motors.
Another general note- The new machine has jam nuts on all the set screws. This is a small thing, but it really makes a big difference in the daily running. My old machine had a single set screw that held the tailstock bushing in place. It would work loose, especially if I put a lot of force against it during drilling. The patriot has 3 set screws holding the bushing in place and each one has a jam nut to keep it tight, so no more fooling around with that.

[dgapilot]

Having the flanged nut sure looks a lot easier than the old style with 2 round nuts and no positive way to force them apart!

[smallblock]

Dga,
You should contact Shopmaster- they might have those flanged nuts in stock to fit older models. When I got the LH screw, the nuts came with it.