My First Machine Started...FINALLY

[mb0978]

It has been an agonizing road but I finally started my build on May 1st. I was starting to get depressed by the fact that I was spending many an hour reading in the Zone but not taking any action. I couldn't make up my mind on a design and when I finally thought I had decided, I couldn't make up my mind on what improvements I should make. It became clear I better get off the pot and do SOMETHING.

I decided on building the jgro machine since the plans were so detailed and it seemed like a great way to learn. I really appreciate the contributions the CNCZone members have made and especially the time, effort, and attention to detail jgro has put forth.

I will be making a few modifications but for the most part it will be very close to the plans. The base will be extended in the x direction to the full width of the machine and there will be a bottom skin on the base box. The bed support box will also have a bottom skin. The x rails will be 1" gas pipe and the z rails will be 1" drill rod since I had some on hand. I decided on Lovejoy connectors as an easy way out and the lead screws will be 1/2" acme rod.

I went to the surplus store and found some assemblies that look to be PVC. They yielded enough parts to make all the rail adjustment blocks. The first pic shows a test piece with only two screws holding a rod. I would guess I am exerting at least 150 pounds of pressure on the rod and it has no problem holding that weight. The PVC is quite distorted from the screw pressure, but it is holding quite nicely.

The second photo shows the material for both torsion boxes cut and ready to be assembled. I used Cutlist32 but screwed up on one of the cuts so I wasn't able to get the bottom skin out of the 5x10 1/2" MDF sheet. Home Depot wouldn't sell a 1/4 or 1/2 sheet so I opted for using a piece of 3/16" hard board I had on hand.

Apart from trying to learn TurboCad to make the modifications necessitated by the larger diameter rails, that pretty much sums up the first week.

Mike

[mb0978]

In the second week, I finished the base torsion box and put on a couple of coats of shellac. It didn't come out really flat as I didn't have a good flat surface to build it on. I should have read the DIY article closer and paid more attention. It will be interesting to see what compensations I will need to make to make up for the inaccuracies.

I have started the linear bearing assemblies. Picture 1 shows the milling operation for the flats. I would sure appreciate any tips on how trained machinists would perform this operation. The best method I could come up with for holding the piece was the angle block.

The rail adjustment blocks have been completed. My wrist was killing me after hand tapping those 48 holes. Picture 2 shows the completed blocks as well as the linear bearing assemblies in process. The bags in the photo contain all the fasteners for the project. I was able to get the whole lot for about $12 at the same surplus store where I found the PVC.

And so ends week 2...

Mike

[mb0978]

Week 3 was slow but I did make some progress. The linear bearing assemblies are complete. It will be very interesting to see how they fit since I have changed the x and z rail diameters. It looked good in TurboCad but they were my first CAD drawings which means I don't know what I am doing.

Mike

[mb0978]

I finished the bed support torsion box. This one came out pretty darn flat and boy is it sturdy. I also finished cutting the 3/4" MDF parts. The photo shows the base torsion box, bed support torsion box, and all of the 3/4" MDF parts cut and ready for the next step.

Mike

[mb0978]

jgro, you and your plans ROCK! This is the first time I have built anything from drawings and it is so nice to have such detail to refer to.

I made good progress on the x and z assemblies as seen in the first photo. I must have pushed the z axis back and forth a dozen times because it is COOL to have movement!

To drill the holes, I assembled the parts as seen in photo 2 and drilled the .201 through both parts. After disassembly, I opened the through holes up to the .281 size. This seemed to work very well as the alignment was perfect upon reassembly. For dowel pin holes, I only drilled the through hole and will drill into the second part after everything is aligned.

To drill the larger odd sized holes, I used a boring head as shown in photo 3. These holes had to be opened up from the 1" in the plans because I went with 1" drill rod for the z axis instead of the .84" gas pipe.

I also used the mill to cut the dados. I used a 1/2" two flute end mill and it cut beautifully. I know it took longer than a tablesaw or router, but it sure was a lot quieter. I'm trying to learn the basics of milling so I'm using it whenever I can.

I had some issues with the Super glue on the tapped holes. In a few cases, I must have put too much in and it pooled at the bottom of the holes. When I went to re-tap after the CA had dried, it gummed up the tap and blew out the hole. I had to soak the tap in acetone to get all the crud off. To fix it, I installed some threaded inserts as seen in photo 4. I drilled out the hole and then used a cut off hex key in the mill to thread the insert into the hole. Luckily I tested this process before working on the actual parts. My first several tests ended in split parts until I got the drill size right and clampled the part properly.

I still haven't worked out the motor mounts or lead screw mounts. I'm going with 1/2-10 Acme on x and y so I need to deviate from the plans. Also, since I'm going with Lovejoy connectors, I need to make a standoff motor mount.

This is really turning into an obsession now!

Mike

[paulC]

Great work. You are making good progress.
Keep those pictures coming.
Paul

[mb0978]

Thanks Paul, I appreciate the kind words.

I started playing with the alignment of the z axis rails tonight and found I couldn't get all the bearings to touch before I ran out of adjustment. I decided to take the x bearing mounts off of the x axis platform so I could put the platform on the surface plate and check the measurements with a height gauge. The dado joints were so tight that I ended up drilling six more holes through the x platform so I could use dowel pins to force out the bearing mounts. I was afraid I would booger up the threads if I used the existing holes.

When I took measurements I found the left rail was within .005" between the top and bottom plates. So was the right rail. I guess it was the .040" difference in height between the left and right rails that caused the problem. Doh! Even though I used a surface plate, angle block, and height gauge to make the layout lines, I was able to screw it up. What a dork. I cut new top and bottom plates and am in process of doing them right this time (hopefully).

The wife is leaving for 17 days tomorrow so progress will probably slow way down as I have to attempt to not only take care of myself but also my daughter

Mike

[94vette]

Looks like your making great progress. Have you decied on what size motors your going to use?

Maybe you could have your daughter help you with the build. It would be good "bonding" time.

-john

[paulC]

I cut new top and bottom plates and am in process of doing them right this time (hopefully).

Mike

Hey, shiz happens. At least you are making progress.
I would have thought bigger holes for your rail adjustments would have been the easier solution. Just bore or file them out a bit.
Thats one advantage of MDF, you can cut away bits that get in the road.
Paul

[mb0978]

Thanks John, at times I think it is great progress but then reality sinks in when I look at what is left to do. I bought a 125 oz-in Hobby CNC 3-axis package 2.5 years ago. I put it together but then I started down the path of research and indecision and lost interest. I'm going to stick with that package for now and see how it performs. The case and transformer in the photo came from a local surplus store.

John, that is a great idea about getting my daughter involved. I talked to her tonight and she said "I'm not to good at building machines" but I did get her interested in helping me paint it. That may be a fatal mistake though as her favorite color is purple.

Paul, you said it. It just sucks when it happens to you though! I pondered enlarging the holes and taking the easy way out but I am looking at this project as a giant learning experience. It will benefit me more in the long run if I try to do things over the right way. That way I'll hopefully discover my limitations and use that knowledge when I build the second machine.

I finished reworking the x axis top and bottom plates. They came out much better. With the z rails resting at the bottom of the holes and only slight inward pressure on the adjusting bolts, all the bearings are touching. As the photo shows, I have plenty of adjustment so I think I will be ok this time. I'm just too beat right now to attempt any further alignment. I couldn't help but push it back and forth another dozen or so times

Mike

[paulC]

John, that is a great idea about getting my daughter involved. I talked to her tonight and she said "I'm not to good at building machines" but I did get her interested in helping me paint it. That may be a fatal mistake though as her favorite color is purple.

Mike

You could call your machine Barney, but then you don't really want to end up with a dinosaur. Plus I hate that character
Paul

[mb0978]

You could call your machine Barney, but then you don't really want to end up with a dinosaur. Plus I hate that character
Paul

LOL!
When I brought that up with her she said, "Dad, I'm almost 10. Besides, Barney got cancelled because he said the "S" word on live TV." I don't know, check out photo #1, it is starting to grow on me.

Made some decent progress this weekend. You know you are getting somewhere when that daunting pile of fasteners starts to dwindle. Man, there sure is a lot of drilling and a boatload of tapping.

I was playing with the linear bearings trying to figure out how to get them even. I ended up putting them on the surface plate and using the height gauge to measure each bearing. It took a while but I managed to get all four bearings within .005". When I placed a hunk of drill rod on the bearings and measured the height in several places, it was within .002" or so.

Everything went together pretty well. I had one through hole on the gantry front that was misaligned and need to be "opened up" a bit. The drawings don't show how to mount the end supports to the torsion box and the bed support torsion box. I drilled some through holes in the end supports and plan on putting threaded inserts into the 1/2" end pieces of the torsion boxes. I also drilled some holes for dowel pins.

I am waiting on the 1" gas pipe. My neighbor owns a fire sprinkler business and has promised me some of his rems. I still need to design the motor mounts and leadscrew bearing mounts and make the anti-backlash nuts.

I can't wait!!

Mike