why not line up the cores for the box like the 2006?
Hey everyone, I will be starting to build the 4'x4' Hybrid soon. Right now I'm designing an MDF torsion box base for the machine. Here are the designs so far (they are based off thewoodwhisperer's design):
why not line up the cores for the box like the 2006?
I decided to go with the torsion box table because I loved how stable it made the Joe's 2006. When you say line up the cores do you mean have interlocking interior ribs? Or do you mean just keep the interior grids in a straight line?
I considered interlocking them but it would be so much extra work routing/slotting each rib to have them fit together. It really wouldn't add much in terms of stability I don't think by interlocking them.
However, as advised by madtownrob I am going to change the design and line-up the interior short grid pieces and not stagger them. So I will be modifying the design tonight to keep the short pieces in-line. It won't be too much harder to do this, I will just have to toenail them.
The table is based off of this design: http://www.taunton.com/finewoodworki....aspx?id=28855
I did some calculations on the weight of the torsion box top:
I just did some calculations on the weight of the Torsion Box Top:
- (1/2" MDF) = ~ 2.5 lbs per sq ft
- (3/4" MDF) = ~ 3 lbs per sq ft
So for the interior grid (1/2" MDF) there are the following parts:
(63) 7.25" x 3" x .5" Short Grid PieceSo I did the following math to calculate their weight:
(8) 57.5" x 3" x .5" Long Grid Pieces
(144/2.5)=(21.75/x) so x=.377 lbs per short grid piece .377*63=23.789lbsThe outer frame of the grid (3/4" MDF) includes the following pieces:
(144/2.5)=(172.5/x) so x=2.994 lbs per long grid piece 2.994*8=23.985 lbs
(2) 3" x 59" x 3/4" SidesTo calculate weight:
(2) 3" x 69.75" x 3/4" Sides
(144/3)=(177/x) so x=3.6875 for (2) of the sides so 3.6875*2=7.375 lbsAnd I am not going to show the calculations for the skins but (2) skins should = 144.94 @ (72.469 lbs per skin)
(144/3)=(209.25/x) so x=4.359 for (2) of the side so 4.359*2= 8.718 lbs
So all together the torsion box top should be:
23.789 + 7.375 + 8.718 + 23.985 + 144.94 = 208.807 lbsFor a more in depth view at the torsion box table build I am doing a more detailed work log here: http://woodwhispererforum.com/showthread.php?t=1702
So including the hardwood wrapping around the edge of the torsion box the top is going to be ~215lbs !
I'll keep you guys updated,
Last edited by Sbthomas13; 03-20-2009 at 12:18 PM.
Hi Spencer - it is good to have you back and building again.
If I may, I would like to suggest a possible alternative to the MDF torsion box construction. It is true that the torsion box is a conceptually strong design with a number of benefits. I don't like building them, mostly because it is too much work to make a nice one.
As an alternative, may I suggest instead to use a single sheet of structural panel. There are both foam core and honeycomb core versions of these, and even 1 inch thick of these boards is stiffer and flatter than most any MDF torsion box.
Here is an example of the Al honeycomb version: http://pacificpanels.com/
It is not an inexpensive material, but there is a lot of scrap generated when it is cut to size industrially. I managed to drive over to this place and get some scrap for free from the owner for my son's science project. (some I still have for my build)
The foam cored material is actually quite strong as well, and you can get it with either MDF or plywood skins.
Anyway, good luck on whatever path you pick.
I like the interlock like joes design for the 2006. Here is how I would do them if I were doing them.
Cut all the strips to final length.
Setup the table saw with the dado blade. Set the fence for the first cut.
Stand them all on edge and clamp them together. Run the stack through the dado all at once. Repeat until done.
To me it would be more of a pain to try and put together a box without the interlock to line them up and hold them in place as you build.
Either way, good luck on your build.
It's been a while since I last updated this thread, but since my last post I was able to complete my build of Joes 4x4 Hybrid. I built the machine for my senior graduation project and I have to say I'm very proud of it and how it turned out. I'm extremely grateful and appreciative of everyone who has donated materials, advice, and knowledge to my build. I couldn't have done it without you guys!
So heres an overview of the build:
First I finished building the torsion box assembly table that I decided to use as the base for my machine. I liked the assembly table because it provides extra storage space and is very stable. It is made out of 3/4" oak plywood and an MDF torsion box that is wrapped in oak w/ a hardboard top.
After the table was completed I moved on to building the carriages for the machine. I cut out all the MDF parts on my schools CNC. I then glued together the carriages, sealed the joints with some filler, sanded them, and then primed them.
I then painted them bright blue.
After the carriages were completed I moved on to preparing the metal for the machine. I drilled, cleaned, primed, and painted the angle iron for the machine. With a simple fixture on the drill press this was very easy to do and didn't take much time at all. After everything was painted I was ready to start assembling the machine. First I mounted the strut channel and aluminum extrusions on to the base table. I made sure the Y-Axis rails were parallel to each other.
I then fabricated the bearing pressure plates and attached them to the Y-Axis carriage. Next I mounted the carriage onto the rails and adjusted the bearings.
I then mounted the X-Axis extrusion onto the two Y-Axis carriages. After that I had to attach the bearings to the X-Axis carriage. Then I mounted the carriage to the extrusion and adjusted the bearings. Next I fabricated the Z-Axis slide and installed it on the carriage.
Next I attached the HDPE motor/bearing mounts to the aluminum extrusion.
After that I installed the leadscrews, leadnuts, and motors. Next I moved on to designing and fabricating a controller enclosure. I drew up the designs for it in Rhino CAD software.
I then cut out the parts for it using my school's laser and CNC router.
I then glued together the parts, applied bondo to the seams, and sanded it. Next I primed the enclosure and painted it an aluminum color with Rustoleum High Performance Enamel which is awesome spray paint because it drys super quickly.
I then transfered the electronics from a 3-axis Keling controller and added a fourth driver for the fourth motor needed on the Hybrid. With a little soldering and some heatshrink I was able to get the controller put together pretty quickly. I wired in a blue LED fan too.
After the controller was completed the only thing left to do was extend the motors and tune them. This didn't take too long and the motor tuning was very easy to do.
So here are some pictures of the completed machine:
Here are some pictures of it cutting a BMW logo. It's a simple 2D cut but it still proves the machine works. This machine works just as well, if not better, than my schools Techno-Isel CNC router. I am very pleased with the results.
To anyone considering building a Joe's 4x4 Hybrid CNC: DO IT!!! I would highly recommend building the hybrid because it has arguably the best performance specifications of any DIY CNC on the market today. Also, it is very simple to build and there is great support available on the private users' forum. You won't regret building a Joe's 4x4 Hybrid: The plans are excellent, the build is exciting and fun, and it's an experience that I'm sure I will remember for the rest of my life. I'm only a senior in high school but I had no problem building this machine and hopefully soon I'll be using it to make some money for college! Thanks for taking interest in my build!
Looks great, Spencer.
Congrats on a great build.
Out of curiosity, what was the end cost (excluding the software)?
mmmm. I'm guessing you will get an "A" on your project - maybe two. Great build.
Nice work, man. It looks very clean. I'm also curious about your total cost as well.