[DieGuy]

How about something like this?

[mikeschn]

Steve, I put my gantry together and noticed some problems. It does roll front to back. When I had it together before, I couldn't put any force on it to notice. I'm going to make some side panels, that fit around the box and tubes, and attach them after the threaded rod is tightened. These along with a rear panel (and probably a front panel behind the router) should stiffen everything up. Mike was by to take a look, and I think he agreed with me.

Yep, I gotta tell you guys... Gerry has one heck of a nice looking machine! Once he boxes in the bridge, I think all his wiggle movement will be gone. It's encouraging to see his bridge moving on the gantry rails. There was no friction at all. Combine that with a 2 start acme screw, and you've got a machine that'll fly. I'm looking forward to continue on my machine.

Mike...

P.S. It was real good to meet Gerry. He's a real professional, and has lots of good ideas too!

[chronon1]

That is really cool .. putting the whole in the bolt head to make the ecentric .. whod of thunk it ? u must be a machine / tool and die guy !

that bold head should probably me a high strength bolt ( designated with 6 strikes across the head not 3 ? ) but then it's kind of a pain to drill with the higher carbon steel -- more dull bits to sharpen in the grinder ;(

Howdy to all,

Sorry, I didn't get to do much yesterday on the zone but a fellows got to make a livin' sometime.

I finally had some time in the workshop yesterday. I managed to throw together one of the eccentric bearing bolts that I have mentioned in previous posts. I shot some pictures but I have never posted pictures on the zone so I hope it works.

Materials list and the dimensions of the parts:
Bolt: 1/2"x 1" with nut. Actually on the machine I would use a nylock nut.
Standard skate bearing.
Bearing bolt: 5/16"x3/4" Flush or Flat head bolt
1 standard 5/16" washer.

This setup gives over 3/16" of easy adjustment!

[Aras]

Hi, I'm new to the forum and I thought I'd share some info from my recent research efforts.

I've been looking for linear slides recently and I came across a German company called "Hettich" who make loads of things including heavy duty drawer slides that range from 10kg to 136kg load capacity. They are reasonable priced (depending on the complexity and load bearing ability) plus they are available at my local hardware store in Sydney, Australia.

Here are some pics I found to give you an idea (results of Google image search for "Hettich slide" or "Hettich quadro"):
Quadro End View
Quadro rendering

The "Quadro" range looks really interesting because it looks like it will take loads from all angles.

I've ordered a couple of the normal ball bearing, 450mm long, 45kg models from an Australian supplier so I can evaluate them. They cost about AUD$27 each. I was hoping to mount them end-to-end and see if I can extend their range.

Check out their
"Hobby Tip 4 - details of drawer slide systems"

Their websites are a pain to use, but the Australian one is OK:
Quadro
Ball bearing runners

Share the knowledge!

regards,

Aras Vaichas

[Jimmy Southern]

Hi Everyone,

Looks like we have had a bit of progress.

So far I am leaning toward the design sketch by Dieguy. Couple of changes, 1st add one more bearing to each of the axles at least on the top ones. 2nd use the eccentric bolt on all of the axles. I believe this would give enough adjustment to get every thing in perfect square and level.

I also noticed someone was having moisture problems on the wood. This is my recommendation: Most hardware stores carry polyester resin for doing fiberglass repairs. Coat all of the MDF sheets with this before doing any cutting. this will seal the majority of the board. The only problem with this is, the edges may swell slightly if you wait to long to cut it up after coating. After you have cut and glue assembled your parts go back and coat all exposed(open) MDF with the resin. After a couple of coats you could drop this in a lake and not bother it with moisture.

Chronon1,

No, I am a signmaker by trade. I am a tinkerer by genetics and neccesity . I don't think we will exceed the strength of a grade 3 bolt. If I remember correctly, the shear strength for a grade 3 bolt is almost 20,000lbs, in a 1/2" size. The maximum rated load limit for the bearing is 1000lbs and this is shock load rating. Not to mention we have not even discussed the 5/16" bolt that holds the bearing to the 1/2" bolt. So I don't think the weak link is the grade 3, 1/2" bolt . If this were for major lifting or load carrying I would agree. But for an MDF based machine I believe it will hold up to the strain. The only thing I would do to increase strength would be to move the hole a little closer to center. The example I posted was a bit to close to the edge. I didn't ever measure I just "eyeballed it" .

Hope this helps,
Jimmy

[DieGuy]

Hi Everyone,

Looks like we have had a bit of progress.

So far I am leaning toward the design sketch by Dieguy. Couple of changes, 1st add one more bearing to each of the axles at least on the top ones. 2nd use the eccentric bolt on all of the axles. I believe this would give enough adjustment to get every thing in perfect square and level.


Hope this helps,
Jimmy

Thumbs Up Jimmy, make sure you take pictures and let us see you progress.

I am also looking at one that is a bit more radical. I want to model it and try it before I offer it up. It is really not a garage store type design but could be produced for very minimal cost. I think I will try it on a small router setup to see how it works out.

[mikeschn]

I worked on the bridge this morning... It's totally boxed in to try to avoid any movement problems.

Next I'll work on the tool mounting, and finally I'll come back and see if we left us any room for the stepper motors and acme shafts.

Mike...

[mattbyrne]

Great work Mike! Are you using Solidworks? Any chance you can make your models available.

[mikeschn]

Great work Mike! Are you using Solidworks? Any chance you can make your models available.

Actually, that's modeled in UG NX. But I can export a parasolid if anyone is interested. I'd like to get the basics of the machine modeled before I start exporting... Can you read parasolids? How about acis?

Mike...

[ger21]

I worked on the bridge this morning... It's totally boxed in to try to avoid any movement problems.

I think you'll get a little front to back flex, depending on the loads involved. A 1/4" plywood panel on each side should be enough to prevent this. Easier to do it now than find out you need it later.

[spalm]

I agree with Gerry. Maybe you could also make your pink plates and the top and bottom of the Z out of the same piece of wood to strengthen the Z.

Steve

[Jimmy Southern]

Hey Mike,

Mike, I really need you to do me a favor. Please look at post 241 and my post 245. If you have some time I need to see a quick 3d rendering of the idea with the changes I mentioned in post 245. If I use this I will probably use 1-1/2" angle iron. This will also help the other builders who are thinking of this as an option.

Don't spend alot of time on details, I just need to visualize it with the sizes and spaces correct, to make sure there are no interferance problems.

Let me know if you can do this. Also if you need any more information pm me or just post it. I usually check back 3 or 4 times a day.

Thanks a bunch,
Jimmy Southern

[ger21]

Jimmy, DieGuys idea does look pretty good. I didn't pay much attention to it when he first posted it. It won't be any easier to cut perfect matching 45° angles on all those parts. It may een be more difficult than drilling a hole in each one, as the angle needs to be perfectly at 45°. Looking at Mcmaster Carr, i also noticed that angle iron has a thickness tolerance of ±.01, which is quite a bit.

Also, I'm not sure of it will prevent the forward rocking that I'm seeing.

[DieGuy]

Jimmy, DieGuys idea does look pretty good. I didn't pay much attention to it when he first posted it. It won't be any easier to cut perfect matching 45° angles on all those parts. It may een be more difficult than drilling a hole in each one, as the angle needs to be perfectly at 45°. Looking at Mcmaster Carr, i also noticed that angle iron has a thickness tolerance of ±.01, which is quite a bit.

Also, I'm not sure of it will prevent the forward rocking that I'm seeing.

I think it has to be more ridged than the round tubing design, the bearings have full contact and any deflection ony increase the pressure on the bearing where with a single point contact on round tube the possibilites for rolling about the tube axis increases. That is impossible on a V.

The tolerances on angle iron are large but generally I have found that mostly those apply on a piece to piece or even a run to run basis in the manufacture, single pieces tend to be much more uniform, typically the same within 0.001. One might even consider Aluminum angle, the full line contact of the bearing would tend to prevent galling.

Alignment tends to be easier. Simple Sheet metal shims placed behind the angle can be used effectively to adjust the location of the angle so perfect cuts are not really necessary. Even a dab of hot glue can be applied to prevent the shims moving out over time. Several options can be use to create the angles, but I think that rough cutting the angles on the stock and assembling the torsion box and then making a jig to hold the router @ 45 while using a straight edge clamped to the top/bottom of the torsion box would work great. A good finish reference plane is established with the torsion box and the straight edge is a natural for the other axis of freedom.

[ger21]

It'll definately be more rigid than round tubing. As for the tolerance, that's what I was thinking.

[achiestdragon]

hmm
an idea for making the angle iron method adjustable
and removing the need for a 45deg cut
use 2 square bits of mdf rotated through 45deg and bolted to the torsion box
if slotted holes are used then this would allow for adjustment

there may be a better way but this seems both easy to make and solves the problems in having to cut a 45degree angle and also allows for alignment

dave

[Jimmy Southern]

Hey Dave,

I like the idea! But I have a question. Do you have the capability of doing a quick 3d rendering? there are alot of people who have a hard time visualizing the 2d stuff. Also for the plans, if nothing else we could include this for an optional build idea.

Also what size angle did you have in your design? I believe it needs to be at least 1-1/2" for the large machine. I know the torsion box design is self supporting but I also know MDF. I only have a dxf viewer, no capability to see measurements. I really wish I was good at cad work. It would make sharing ideas so much easier.

Gerry,

What do you think about this? I like the idea of being able to add more than one bearing per axle to eliminate the wear tracks in the rail. I really think we are on to something here.

Everyone let us hear your opinions.

Thanks,
Jimmy

[Rance]

...maybe someone has an easier way.

http://www.sears.com/sr/javasr/produ...id=00945560000

FINALLY, a good use for those strap wrenches.

Rance

[ger21]

Jimmy. I wouldn't add any bearings. It would be virtually impossible to set them up to carry the load equally, imo. and if you use steel angle, wear should be negligible.

[DieGuy]

Hey Dave,

Also what size angle did you have in your design? I believe it needs to be at least 1-1/2" for the large machine. I know the torsion box design is self supporting but I also know MDF. I only have a dxf viewer, no capability to see measurements. I really wish I was good at cad work. It would make sharing ideas so much easier.

Gerry,

What do you think about this? I like the idea of being able to add more than one bearing per axle to eliminate the wear tracks in the rail. I really think we are on to something here.

Everyone let us hear your opinions.

Thanks,
Jimmy

I have to agree with Jerry on this one that wear will not be an issue with steel angle.

1 1/2" angle should give plenty of strength and room to make attachment.