Second machine design process

[yukonho]

A little more work done.
I trial fit the table and it fit perfectly! Rolls nice and smooth on the pipes. Also went to Canadian Tire today to get some spring clamps and came away with a two speed Rotozip!@ Regular 140 (CAD) on sale for 80! I plugged it in and it is quieter than the Dremel! So now I will have a much more rigid spindle that can take 1/8 and 1/4 inch bits, has a 5 Amp motor and two speeds, and is quieter! Should have no problems fitting within the enclosure, it is only about 1/2" longer than the Dremel. I will probably get an aluminum bracket made to mount it.
Also got my Acme 3/8-12 lead screws. Just a matter of balancing time to put it all together. Stay tuned pics to come/.
co

[yukonho]

Here it is as it sits now.
I am super happy with the design still. I would still prefer to use some real linear ways, but the steel pipe will do very well in this setup, especially supported by the torsion box on the long axis. I made supports for the pipes that support the table, but I am not going to use them. I can put all my weight on it, and I cant see any flex. This must be because the bearings are so far apart and never more than 12 inches from the supported ends.
co

[yukonho]

Here is the table. Torsion box idea here again. Like the X axis torsion box, I will fill this with my ground up rubber (thanks again JB) It will add mass and absorb any vibrations. The middle boxes will remain empty because that is where my Acme leadscrew will go.
The foam you see in the corners is polyurethane glue I used to glue the box together. THere are a whole bunch of screws holding it together too. I want this thing to be rigid and dead!
co

[yukonho]

And finally, the bearings for the X axis. The torsion box idea rocks. It completely eliminates any and all flex on the longest axis. I could use a better way to adjust the tension of the bearings, but I will have to settle for shims. These angle brackets will be bolted the same way the ones on the table are. I just drilled and tapped a hole in the corner of the angle, and bolt it through the MDF. They dont take a whole bunch of force, in fact, they pretty much hold themselves in place, so I am not worried about stripping the threads.
The torsion box is not bolted in place yet, (have not exactly figured out how I am gong to do that) I have to align it first, and then attach it securely. I left the gas pipe long so I could use the 4 jaw chuck idea if I need to. Hopefully I wont have to.
Up next, leadscrews and leadnuts!
co

[drawbar]

Can you give us any details on your Z-axis slide?

[yukonho]

Bought the z slide off ebay. I got two of them, but only use one for this machine. The other one is collecting dust.
Really robust unit, it says MicroSlides, inc. Westbury NY, there is even a phone number on it, not sure of the area code I think 516 or 518 and 334-4180 I am sure it would be easy to look up the area code.
Model # 2060
I might consider selling the one I have remaining. I got the two for 60, (Shipping was a bunch and cross border fee's too)
Let me know if you are interested and we can work out a price.
co

[grempel1]

Hi,

This is my first post and since I have been following your journey with interest, I decided to intrude on your thread since much of my design builds upon your experience.

First, I just wanted to comment on the discussion about gas pipe and smooth pipe and so on. Seeking inexpensive and smooth, suggests to me another alternative, namely store fixture clothing rail. This is the chrome-plated pipe that host most men's clothing, expecially suits, sports jackets and coats. It comes in 8 and 10 foot lengths and costs not much more than a dollar a foot. At 1 1/4 OD it also exhibits monocoque characteristics. I would assume that its chrome surface would be considered smooth enough for the purposes at hand.

I am in the process of finalizing the design of my FIRST CNC router and unfortunately I am trying to make decisions about things that I have not experienced. So given your thoughtful overview, I though I would solicit your advice based on your experience. [Besides, I just don't have enough time left to make every mistake that inexperience would suggest]

I am looking to build a fixed-gantry, moving-table router designed to cut deep-relief (z > 8') male, foam plugs. While most cutting involves say, blue foam, on those rare occasions where the foam does not sustain details, the surface is sprayed with something akin to a primer and the detail is rerouted with a 1/32 or so offset. That would represent the maximal side thrust.

I am hoping for a usable table dimension of 36 x 24 inches.

Using 1 1/4 pipe, would you suggest skate bearings or cam followers. What size?

Should the pipe be located at the outer edges of the table as per your design or set under the table, set in say 9 inches from each edge? Should the bearings be set at the edge of the table as per your design or should they be set in say 1/4 of the distance from the edge of the moving table. I assume that since any forces generated by the routing will be lateral rather than vertical, that therefore the orientation of the the bearing sets should also be lateral (like yours) rather than vertical (with the "v" and the bearings above the pipe)

Since my activities will be restricted to routing foam, would you see any advantage to the use of your torsion box rather than a simple table? ? ? On the other hand, given the leveraged force that will occur from the 8" usage z on the gantry itself, would you suggest a torsion box made of wood or the use of square or rectangular metal tubing for the gantry structure?

The workable answers to these questions should get me quite a way toward completing the structure of the router.

Thanks in advance.

Rgds,
Gary Rempel

[vacpress]

yukonho

nice machine. i like that you accept MDFs weakness and make torsion boxes for everything. i build furniture occasionally and have always thought these mdf machiens here were lacking some of the stiffness of a couch with a good cross-support design...

itll look great painted....

[yukonho]

Well, it lives.
Machine number two roared to life today. It will need some upgrades in the near future, like a better spindle mount and thrust bearing mount for the Z, as well as there is some backlash on the Y axis and some play in the X. By some, I mean a little tiny bit, but noticeable. The hardest part of using pipe and bearings is getting rid of all the play. I ended up using some hard rubber spacers which work OK, but leave a little flex in the system. Will be looking for a better way in the near future. I think the answer for the X will be an aluminum carriage with adjustment slots built in. It is pretty much impossible to do that with MDF.
Looks like I got the alignment pretty good too, I will have to double check it to make sure.
Speed is up, 74 "/min rapids on xylotex board and 3/8 - 12 Acme leadscrew with 24 V going in. I will be cutting my first parts tomorrow ooeeeee cant wait.
Still have to put the door on and all the little things that make it nicer. Cant really see myself taking the time to paint it, we will see.

[yukonho]

Grempel1,
If you are going to have such a big table (and that is BIG) you will need to support your rails. I cant think of anything wrong with laying the pipes on the bottom and having your table ride on top of it. If you have a heavy enough table, and you will, it is unlikely to lift. I have a small enough table that I dont have to have the slides underneath, but it would provide more even support for a bigger table.
I cant say enough about the torsion boxes. My first router, the flexomatic 2000, had a 36" long X 14" wide MDF table made from 1 piece of 3/4" MDF and it flexed EASILY. I can stand on this and cant see ANY flex at all.
By the way, the torsion boxes are filled with ground up rubber to add mass and absorb some vibes.
The pipe you suggested should be fine if it is rigid and hard enough not to dent under the pressure of the bearings. You will need to support it over the lengths you are talking about. My concept for the X axis with a pipe on top and bottom (not my concept, I borrowed it from somewhere else on this forum, just my execution of someone else's concept) pinched by the bearings on the carriage, works great. There is no flex at all, and it was simple to build. I just got the wood cut at Home Depot on their panel saw when I bought it. If you are only doing light cutting, this will be more than rigid enough, no need for metal I would think.
I am not up on the Cam followers concept, so I cant comment on that, sorry. Honestly, if I had another hundred and fifty bucks to throw at this thing, I would use DriLine (sp?) linear slides. Really, the pipe and bearings can be a pain but it is cheap.
I hope I touched on all your questions, please feel free to throw more at me.
What are your foam plugs going to be used for?

Thanks for the compliments VacPress. I am super happy with this one, now to see if it will do everything I want it to.....
co

[johntbyrne]

Of course I'm interested in how the rubber worked out. May be no way of knowing improvement unless you built one without rubber but what do ya think now that you have it up and running?

Cheers
John

[Hobbiest]

Gary...I would be worried about the clothes pipe denting along its length where the bearings ride. I is usually pretty thin wall stuff.