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    Viper,

    If I am understanding you correctly, on the adjustability, I think if you use a master template to route all of the pieces then the only adjustment that should be necessary would be to the bearings on the gantry & the z carriage. Everything else should be very consistant. You may have to shim in a few areas but I don't think you would if you assembled the machine carefully, paying close attention to the alignment of the pieces and to the squareness of the parts.

    If the design is well thought out it should go together almost like lego blocks. We should design this to have half lap joints in the torsion boxes so it goes together like a drawer divider. this will greatly eliminate the build errors.

    Hope this sheds some light on the idea that I have
    Jimmy Southern



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    Registered pminmo's Avatar
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    May I suggest that if your going with black/gas pipe that you size it to commercially available cutoffs. Usually available in 1' increments. For a machine base, consider using 3 sheets of MDF glued/laminated, that will give you strength and weight for stability. Those that don't have a table saw will be pressed to do a good torsion box. The only thing you need there is a flat surface or jigged support.

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    what happened to the KISS principle .. and also First things First.. the simpler contains drawer slides, smaller, cheaper and less complex ..

    it makes common damn sense to see how the simpler proof of concept can be completed before undertaking the whole gas pipe and roller blade bearing design..

    start small and go forward.. remember, "He who is faithful in a little, can be faithful in alot."



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    Well actually, we are going to do both, the drawer slide and the black pipe designs. Both designs will be hardware store based, and also no mill required.

    Here's what I am working on for the black pipe design. Each member of the torsion box will have an end like this, for adjustability over the entire length of the black pipe. Furthermore, if the holes are not perfectly centered, that's okay, you can center the pipe using the screws. The pipe is going to be 1 1/2" black pipe, currently 3.39 per foot, which has an od of 1.9". So you can drill a 2" hole, and have .10" to play with.

    What do you think so far?

    Attached Thumbnails Attached Thumbnails Hardware store design CNC router #1-pipe_support-jpg  


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    Hi, I am going to try and add a simple thought here, I think Jimmy is refering to a dado groove in the torsion box. Regarding the alignment of the pipe holes in the torsion box, once you measure, mark, and drill the first end piece accurately, you can lay it on top of the second piece and sqaure and clamp it. Then your first piece is a template for your second piece and should give you perfect matching holes.
    As a possible substitute for the black pipe, has anyone looked at the ceiling fan drop rods that have a polished finish and are sized from 6" to 48"? If so, what did you think?
    Thanks, woodworker21



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    Hello everyone,

    Just need to clear up a few things. First I am greatfull to Mike for taking the lead on this. There has been some discussion on the drawer guide vs black pipe and I was glad to hear that we are going to design two different machines. Personally I have no use for the drawer guide machine, it is just too small, so my mind is centered on the larger machine. So don't take my lack of interest as oposition. I am just posting the ideas I have had or seen.

    Now to the specific misunderstandings: The half lap joints are nothing more than half depth dados. Please look closely at ger21's new machine thread. This will clear up alot of questions about what we are talking about.

    Now to the difficulty: I am just guessing here but I think there would most likely be no more than 5 pieces that would have to be precision cut and all of this can be cut with hand tools if very diligent. More tedious than difficult. Once these pieces are cut you simply use a pattern bit, or flush trim bit, to follow the master template. It seems more daunting than it is.

    I would like to see the design team take this machine to the level of ger21's machine just use a little less material and make the plans include either scalable master patterns or very precise measurements. The only variables that should exist would be the thickness of the MDF, Ply or whatever the builder uses, and the available pipe sizes. this will greatly reduce the work that the builder has to do. This design is very scalable up or down and very rigid. Ger21 says in his post that he put his entire weight 220lbs (I think thats right, sorry ger if it isn't) and it only deflected 1/64". Jgros machine has nowhere near this strength. This is why I am pushing very hard for that direction. In my opinion ger and spalm are on the right track for the perfect "usable" machine.

    I am very open minded if anyone has a better idea for this machine, but I have not seen anything that for the price gives the same quality.

    I really hope that no one has been offended by my enthusiasm. I really do plan on building this machine so I would like to be the guine pig(not sure that is spelled right).

    Thanks to Everyone!!!
    Jimmy Southern

    P.S. Keep the ideas coming



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    Registered chronon1's Avatar
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    i DID A little CAD of that nice Rib Mike --- please find attached and see if you
    how it looks ...

    Attached Files Attached Files


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    Hi,

    This end of the torsion box design may be unnecessarily complicated as Spalms design relies on the pipes being stationary, oK, (parallell and Level to the cutting surface} but so is the torsion box hopefully. All the adjustment is on the Bearings which in the case of the Gantry are moved in relation to the Gantry Legs (sides) the Torsion Box cut-outs must support the rail solidly to prevent the slight (but to some unacceptible) flex in the rails. These adjusters of course will do this but so will grouted ( for want of a better term ) with epoxy ends and the rails pulled into place. The end of the torsion box could be like shown with a screw pulling the rail into the opening.

    However without a cantelivered end in the torsion box or leaving the bottom open it will be hard to adjust these bolts and reduce the cutting surface for a given size gantry. If the bolts are needed then it is possibly better to use countersunk screws from the outside. Must stay away from the bearing tracks though.

    Spalm now believes he has cured the problem by pulling the rails together on the ends with allthread.

    Last edited by phillby; 08-24-2005 at 01:41 AM.
    Brian
    The Sawdust Creator


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    Hey guys,

    I spent about a month trying to come up with an easy way to build these torsion boxes. The half lap dados are tempting, but just try to get them all in 3 dimension parallel (alignment) before the glue dries. I tried twice, and gave up. That is why is used the individual spreaders. Gerry’s boxes were a lot larger than mine and he used screws to hold them together. If you are trying to build thinner boxes, I found that the parts floated around a lot.

    I used the base ply or MDF as the ‘base’. Double check this for square. If it was ¼ inch ply, I used double sticky tape to make it lay flat. Then I glued the first stretcher and checked for perpendicular while using my finger to make sure that it touched the 3 edges of the base. I then spread glue on the first set of spacers and squished them into place (placement is not important). I then spread glue on the second stretcher and squished it into place, again checking for perpendicular and using my finger to make sure that it touched the 2 edges of the base. Repeat this along the entire base. The last set of spacers never came out to the right length, so I custom cut them at this point to make sure that the last stretcher was just touching the far edges of the base. I then let this dry overnight before adding the second skin by applying glue and a weight to hold it in place until it dried.

    I did not use a nail gun or other fasteners. Only glue holds the box together.

    Just my $.02
    Steve



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    The basic construction of a torsion box can be seen here...
    http://www.diynet.com/diy/ww_materia...278181,00.html

    Chron,

    Your cad drawing is a good start. The board is 3" x .75 thick. The upper and lower bolts need to be above and below the board.

    I'll start modeling the torsion box this morning.

    The other approach is to let the pipe lay on the bottom of the circular cutout, and just use the other two bolts to snug it up. The only reason you'd need the bottom bolt is if the cutouts are inaccurate.

    When I built my sample rib, I found it very easy, because precision wasn't critical. And all 3 holes were very easy to drill and tap. Oh, and the drill and tap was available at the hardware store too, for $4.39. Throw it in your drill motor and away you go. I would harden the threads with some CA though.

    Mike...

    P.S. I threw a few lines on paper, to get a feel for where I am headed. The bolt size changed from #10-32 to 1/4"-20 (not changed on the drawing yet)!

    Attached Files Attached Files
    Last edited by mikeschn; 08-24-2005 at 04:56 AM.


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    Here's the lower torsion box and the skate bearings... I don't want to go any further until you guys tell me that's what you had in mind, and that we haven't created any weak links...

    Mike...

    P.S. Just added the centering bolts...

    Attached Thumbnails Attached Thumbnails Hardware store design CNC router #1-hardware_store_design1e-jpg   Hardware store design CNC router #1-hardware_store_design1f-jpg   Hardware store design CNC router #1-hardware_store_design1g-jpg  
    Last edited by mikeschn; 08-24-2005 at 10:06 AM.


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    Mike, if you'd like, you can come by and take a look at mine.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Quote Originally Posted by ger21
    Mike, if you'd like, you can come by and take a look at mine.
    I'd like that! PM me your address and phone!

    Thanks,

    Mike...



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    spalm,

    I was just reading your post and had a thought. If the pieces are cut like ger's, it should be a simple matter of putting together the outer shell of the box first. If this is square and true when the glue dries the rest should just follow it's lead. Also the assembly will only be as good as the master pattern. The more time spent making the masters perfect the easier the assembly will be. Just my opinion though.

    Mike,

    I did notice one thing I would change. On the bearing bolts I would go with a flush, or countersunk, headed bolt. This would give a bit more room for the supports to clear. It will also center the bearing on the bolt and take out any play in the bearing itself.

    So far I like it!

    Also did anyone find the eccentric bolt idea that I was looking for this might be handy for the cad guys if we can get them a picture.

    See ya,
    Jimmy Southern



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    About the best we could do is to go with a low profile socket head cap screw.

    I'd like to see a picture of that eccentric bolt too!

    Here's a major question for you guys...

    do you want some kind of built in adjustment plate like spalm has, or do you want all your adjustment in the pipe adjustment blocks?

    Mike...



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    I just dug out the pair of drawer slides I knew I'd scavenged some time back. Turns out that they are Accuride precision units rated 150 lbs the pair, with a retracted length of 28 inches. I'm going for a drawer slide design for my first machine.

    One question for discussion. I am considering angling the mounts so that the slides are 30 degrees off vertical. This way I can assemble with preload without needing thousandths precision in construction. I'm also thinking that it will deal with sideloads better. Any comments?



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    Jimmy, I was just pointing out what I had learned. Note that Mike’s link on torsion boxes also uses individual spacers. Both ways work. Just watch out during assembly time. A couple of things that I was worrying about when building these were:

    Most people at this level do not have a pneumatic nail gun. I do, but I was trying to build to their level of tools. I was using 1/2” MDF and screws at the cross joints did not work to well. Remember if you use Baltic birch ply, it is metric, so you may have to get metric router bits (or adjust cuts) for a good dado fit.

    My most critical alignment was to make sure that the pipe seats were all in line and the box was square. This is a little different than normal box construction as the struts stick out.

    Clamps just seemed to get in the way and can add twist to the box that you don’t realize until it’s dry.

    I like where this is going,
    Steve



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    Quote Originally Posted by spalm
    My most critical alignment was to make sure that the pipe seats were all in line and the box was square. This is a little different than normal box construction as the struts stick out.
    The top and bottom of my torsion box have a rabit along the edge with the tubes. The cross members are notched to allow the rabbit to fit in. By carefully adjusting the rabit, it can only go together perfectly straight. An alternative would be to cut a small slot in the cross members, and also in the top and bottom. Then use a spline during assembly to line everything up relative to the top and bottom skins. You could do this with a table saw or router table.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Gerry, my point exactly. All I wanted to point out is that these boxes are a little different than normal, and probably require some careful thought on how to assemble them.

    Steve



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