[CarveOne]

Progress has been slow today. In the photo below you can see a bolt head in the middle of the rail behind the vertical box tube stiffener for the Z axis rail. There are five of these 5/16" bolts in the rail that attaches the 1" x 2" Y axis box tube stiffener with a nut on the rear of the box tube. The first thing that was needed was to change these so that the bolts are inserted from the rear and thread into the rail with no protrusion to allow the full 1" spacing between the rail and vertical box tube for the anti-backlash nut and lead screw.

After intently studying this for a full 0.5 picosecond or so, :withstupiI decided to just drill a clearance hole for a 3/8" x 1-1/4" bolt and thread the 5/16" holes for the 3/8" bolts. Conveniently, the 3/8" tap needs a 5/16" hole. Imagine that...... I don't have any of the bolts on hand though, so temporary pieces of 3/8" all-thread and nuts were installed from the rear of the gantry as I made each of the corrections to keep everything aligned. I'll pick up the bolts later this evening.

I also need to buy a hardened 7/8" hole saw to bore a hole through each end of the gantry for insertion of the lead screw. I'll probably need some extra clearance to get everything aligned and I don't want to have to enlarge these holes if I make them too small (like 5/8"). The hole saw has to pass through the 2" wide sides of the gantry end support box tube (0.120" wall thickness) and the 0.250" angle corner stiffener. I may end up milling away a small part of the corner stiffener if there is interference with the lead screw.

The alternative is to mount the lead screw on the rear of the gantry and mount the anti-backlash nut on the rear plate that I made yesterday. That requires making two new (and longer) bearing plates. I really want the lead screw closer to the center of mass of the Z axis assembly, and I really don't relish the idea of making two new bearing plates.

CarveOne

[acondit]

CarveOne,

Sometimes doing the design in 3D will catch some of these things but not always or maybe I just forget to actually do it all in 3D. Actually I think putting the Y-axis screw behind has another advantage (less dust catching). Plus you can bolt the bearing plates to your uprights without having to drill a large hole through your uprights.

Alan

[CarveOne]

CarveOne,

Sometimes doing the design in 3D will catch some of these things but not always or maybe I just forget to actually do it all in 3D. Actually I think putting the Y-axis screw behind has another advantage (less dust catching). Plus you can bolt the bearing plates to your uprights without having to drill a large hole through your uprights.

Alan

Hi Alan,

No 3D drawing education on this end but I did draw it in 2D TurboCAD v12. I just didn't bother to work on the lead screw details for the Y axis at the time. I just assumed that it would be like the X axis. I have a new TurboCAD v16 license now, and it has some 3D capability, so I need to start learning it.

Another advantage of rear mounting is that it doesn't interfere with removing the entire Z axis assembly when needed. My biggest reason for the way I started to install the lead screw is that it places it about midway between the Y axis rail and the Z axis rail. It just seems to be more mechanically "balanced" this way with respect to the push/pull forces imparted on the lead screw.

I went into town this evening and picked up the bolts and hole saw I needed.

I'll be working on it some more tomorrow. There will be some issues with mounting the bearing plates directly onto the ends of the gantry either way I mount them, and I may need to make some additional spacers to clear some bolt heads. I'll decide tomorrow how to complete this part of the build.

The X axis lead screws have already been mounted and removed. I don't anticipate many issues with installing the anti-backlash nuts on these lead screws.

CarveOne

[acondit]

Another advantage of rear mounting is that it doesn't interfere with removing the entire Z axis assembly when needed. My biggest reason for the way I started to install the lead screw is that it places it about midway between the Y axis rail and the Z axis rail. It just seems to be more mechanically "balanced" this way with respect to the push/pull forces imparted on the lead screw.

I mounted the Y-axis screw on the front side on my first router and it was a royal PITA whenever I needed to tighten the mounting nuts for the leadscrew nut. I ended up cutting out an ≈ 4" x 6" opening through the support plate for the Y-axis rails to access the leadscrew nut from the backside. Then I had to remember to jog the Y-axis to the middle before I turned it off, in order to work on it.

So this time I am following JoeCNC2006's lead and putting the Y-Axis screw on the backside.

Alan

[CarveOne]

Well, I haven't ruled it out yet. It does make plenty of sense. It's going to cause me to machine two more bearing plates, and that involves setting up the milling machine to bore the pocket and the other holes in them. I have enough steel left for the stepper motor bearing plate and a piece of aluminum for the other end of the lead screw, otherwise I have to buy another piece of steel. These plates will need to be about 1-1/2" longer to extend farther out to the rear.

Doing as you say puts the lead screw behind the Y axis rail and box tube stiffener, and the ABN will be mounted to the plate on the very rear of the Y axis carriages. It is very easy to move the Z axis along the Y axis rail by moving this plate.

CarveOne

[CarveOne]

Well Alan, you (and Joe) won the argument I had with myself over the lead screw mounting. I made some minor changes to the ends of the gantry and will be able to use the shorter bearing plate. I have duplicated the shorter plate this morning so that I have one for the other end of the lead screw.

After my late lunch break I will clean the new plate and paint it. I'll also finish the anti-backlash nut bracket and bolt the anti-backlash nut and bracket to the rear of the Y axis carriage plate. Then I'll run the lead screw through the nut and assemble the bearing plates to the gantry with temporary clamps to complete the initial alignment. Drilling two mounting holes in each end of the gantry will be done once I know that everything is correct. (Empirical Engineering using a transfer punch set and a big hammer.)


CarveOne

[CarveOne]

How's this look Alan?

The lead screw is now mounted with clamps to hold the bearing plates in place. The lead screw is cut to length and is in the correct position to the point that the ABN bracket holes and the bearing plate mounting holes can be marked with the appropriate size transfer punch and that big hammer I mentioned earlier.

The mounting holes in the ABN bracket will be slotted for any vertical alignment that may necessary during final alignments. The bearing brackets will be mounted with 5/16" bolts that will be threaded into the gantry support tubes.

The ABN was a little tight the first time I ran it over the lead screw from end to end with a cordless drill. The return trip was a lot less tight due to a waxy substance that had been removed from the screw and deposited onto the ABN "fingers". The lead screw has a small bow in it, as do the other two 6' lead screws for the dual X axis drive. I can see it when I roll the rods across a flat work table top.

I am completely worn out from this effort today.

CarveOne

[acondit]

How's this look Alan?

The lead screw is now mounted with clamps to hold the bearing plates in place. The lead screw is cut to length and is in the correct position to the point that the ABN bracket holes and the bearing plate mounting holes can be marked with the appropriate size transfer punch and that big hammer I mentioned earlier.

The mounting holes in the ABN bracket will be slotted for any vertical alignment that may necessary during final alignments. The bearing brackets will be mounted with 5/16" bolts that will be threaded into the gantry support tubes.

The ABN was a little tight the first time I ran it over the lead screw from end to end with a cordless drill. The return trip was a lot less tight due to a waxy substance that had been removed from the screw and deposited onto the ABN "fingers". The lead screw has a small bow in it, as do the other two 6' lead screws for the dual X axis drive. I can see it when I roll the rods across a flat work table top.

I am completely worn out from this effort today.

CarveOne

It looks real good. I think you will be happier with this arrangement than you would have been with the other.

Google for info on straightening screws. I had two that were bent and I got them pretty straight (with a bunch of effort).

Alan

[CarveOne]

These have a slight end to end bow, not just a short section of bow somewhere along the rod. I'll see what I can find. Thanks.

I picked up some bolts I needed to mount the bearing plates today, but another machining project needed to be done this evening for someone else who is building a 1913 Flying Boat model for the US Coast Guard Museum in Charleston, NC. Some of my machining work went into the NC-4 Flying Boat model that he already built and delivered to them. I'll do some work for him on a future USCG C-130 model also.

Btw, it's really convenient having the power strip on the end of the work table while building this thing.

The US Coast Guard museum is in New London, CT, not in Charleston, NC!

My brain must have been cross-wired last evening.


CarveOne

[CarveOne]

Well folks, the boss and I have a drop dead delivery date to finish the jet airliner wind tunnel model by next Friday. I probably won't get a chance to work on my CNC build at all this weekend or any evening next week. We may need to pull an all-nighter or two to get this job done. More working hours = more money to get the power supply to finish this CNC router. It may also mean that I can order the steel box tubing to eventually build the steel chassis for this thing.


CarveOne

[CarveOne]

I managed to get two hours time with the machine this evening and finished mounting the bearing plates on the ends of the gantry. There are so many screws and bolts in the top end of the box tube it's having interference issues in the bolts. I had to remove some bolts to drill and tap the new holes. It's needing a little more clearance in the bearing plate mounting holes to allow for some minor alignment range. That will be done tomorrow and I'll also make some changes in the oak dress panels to accommodate the bearing plates.

The Y axis ABN still needs mounting holes drilled and tapped, and the angle bracket holes need to be slotted a little to provide some vertical adjustment range.

Next on the build list is to install the ABNs on the X axis lead screws.

I have been using a cordless drill to run the ABN and angle bracket back and forth during the work this evening. At one point I discovered that I can compress the ABN spring and just slide the ABN and bracket by hand and the 5 start lead screw will start turning by itself since it has such a low pitch angle. I like that feature!

CarveOne

[acondit]

Hey, I thought you were going to give me a chance to catch up. It looks like you're making good progress in spite of your work schedule.

Alan

[CarveOne]

Hey, I thought you were going to give me a chance to catch up. It looks like you're making good progress in spite of your work schedule.

Alan

CarveOne

[CarveOne]

The dress panels were inletted to fit around the new brackets early this morning. Later today I'll cut the clearance holes for the X axis ABNs and stain the freshly cut parts of the dress panels. Then spray the first coat of polyurethane finish on them.

Dress panel - noun - A good looking device for covering up the poorly designed and manufactured areas of a home built CNC machine.

Gotta go cut the yard for the next 3.5 hours.

CarveOne

[CarveOne]

I cut a square hole in one dress panel at the location of the ABN and cut a piece of 1-1/2" angle to use in the hole for mounting the ABN. The dress panel is stained and a coat of clear gloss polyurethane has been applied. Photos later, when the ABN has been mounted.

CarveOne

[sonicwonder2000]

Hey CarveOne,

Do you make models for a living?! I wanna know how you got THAT job - need any more employees ?

[ger21]

Gotta go cut the yard for the next 3.5 hours.

Mine only takes me 2.

[CarveOne]

Mine only takes me 2.

Fortunately I don't need to cut it this weekend and I'll be working on the CNC machine today instead. With luck I'll have the machine mechanically completed by late evening or sooner. Will clean it up and take more photos.

CarveOne

[CarveOne]

All of the mechanical parts are installed now. There is some more adjustments to make and a few holes to enlarge here and there to fine tune the alignments. The weather is supposed to be cooler (69F!) Monday and Tuesday and if I don't work late I'll work on these again in the evenings.

One X axis lead screw has a slight bend about 10" from the end of the rod and the other rod was straight. I removed most of the bend but it is not all gone yet. Will work on that again soon.

Now I need four new stepper motors and a power supply - pronto.

CarveOne

[contactirfu]

I am very excited - just waiting to see the machine run!