A JGRO Rev 2 build without CNC assist

[BMG]

Greetings all.

Many years ago in elementary school I put together a landscape using a knife, lots of cardboard and a contour map. The result was a simple 3D model of the map. Fast forward to now and I am constantly looking for a simple way (without bloody fingers) to transform mine plans into similar models so that accountants and managers can understand without having to teach them how contour maps work. After a few quick searches, I found myself glued to this site at night and scheming to get going on my first CNC machine.

After reviewing my budget, I am going to have to try and strike it out on my own (Jgro plans from scratch). I would buy a kit but every dollar is precious around here at the moment (diapers rank higher on the budget)

Fortunately I have a few tools at my disposal. A router and small table, 10" arbor table saw, a 12" chop saw, as well as a drill press at work. I am also am a competent AutoCAD user so Joe's plans (rev 2) have been great to get my mind a buzzing. Over the holiday week, everything I looked out I was dreaming of it being cut with a CNC machine.

I already bought 2 sheets of 1/2" MDF (figured I can afford to at least attempt the cuts. I have laid out a cut sheet for all the torsion boxes. IF I successfully get through these, then I should be able to get the remainder done.

My plan is to make coarse cuts in the large sheet, then rip out the individual ribs pieces. and chop saw any non square ends. A dado will be used to cut the slots and the top/bottom recess cuts. A template will be used to cut out the ends and the internal punchouts (might leave these). If I can get this far, then I think I will be ok to proceed to the gantry and beyond.

What do you think? Has anyone else tried/succeeded in building the Rev 2 machine without CNC assist? I figured the $35 dollars spent on the MDF and some time in the (now cleaner) garage is worth the initial attempt.

In closing, thank you for the inspiration and perspiration in bringing and sharing your design Joe.

-Excepted from Joe's main log -

Jan 6

1 sheet of MDF done and a good start on a table saw based X axis.

As I mentioned, I am on a tight budget and am attempting to build the torsion boxes without CNC help. So far so good.

Since the X axis has the largest pieces,I started with them. I am simply measuring and cutting and to date I have the 8 short ribs and the 4 long ribs done. I first cut the 4X8 sheet in 2. The cut was about an inch longer than the short rib length. I set up a rip fence on my table and ripped out the 8 short ribs, reset then ripped out the long ribs.

I tried to take Hager's advice regarding cutting extra pieces but due to a screwup on the first rip, I lost my extras. I made the long ribs as a single piece (not limited in cut lengths this way).

Next, I stacks and squared the short ribs, clamped em together then used a 12 inch chop saw to square off the pieces to length in 1 cut.

Next, I set the rip fence on the table to act as a guide for cutting the interlocking slots. Each pair of slots (mirror imaged the cuts) required 2 settings of the rip fence and careful checking of the position. Once these cuts were made, I used the saw freehand to cut out the middle part of the remaining board. One tough this was that my table saw was at its extreme position out of the table (3.2" high) and I took time and care to do this right and safely.

After the slots were cut, I next cut out the recess where the top and bottom parts of the torsion box would go. Here I used my table saw as a mill. I cut a series of kerfs, broke out the inbetween ridges then ran the whole mess back and forth across the table saw to mill the surface flat. All 8 ribs were still clamped together.

After I was satisfied of the kerf cuts, I removed my clamps and repeated this process for the long ribs.

Once done, I test fitted everything. Except for one short rib, everything fit tight. Due to the saw cut depth, I have some problems ribs not completely seating. Since the ribs are tight, I will route out the final 1/4 inch of depth using a router and a crude guide. If I overcut, it should be ok since everything will be heavily glued.

It took me about 20 minutes to rip all the pieces, another 20 minutes to stack square and cut the ribs to length. THe majority of the time was cutting the slots and reseting the rib guide 4 times for the short ribs and 8 times for the long ribs. Started Saterday at 3:30pm til 5, got interrupted with a grandparent visit for my son, resumed around 8:30pm and called it a night at 11:30 after I test assembled the ribs. So almost 5 hours into it.

My next step is to create a router guide frame to shape the ends of the short ribs. I see simply placing a single rib end in the guide - route - flip - route - switch to a new rib. If this works, I will use this also to drill the holes needed in the ends of each rib.

Brian G

[94vette]

It sounds like your making some good progress. Do you have any pictures?

[BMG]

I did not take the camera out to the garage, I was fighting a dust cloud anyway to it would have been screwed up the camera. I am already worried about my laptop. MDF sure does pump out the Dust.

I am going to be limited to 1 or two nights a week at this. Wife drops the kids on me when I get home so trying to get some garage time is difficult. Leaves me plenty of time to think though.

I figured out a simple way to make a repeatable cutting jig(s). I have a Porter cable router with a 5.75 in base. Using a 1/4" cutter, I will create a 2 piece jig. The bottom will hold the rib end in. Over this will be the cutting templates.

For the pipe rests, I will create a paper template that will show the edge of the cut and the edge of the router base (2.875") minus 1/2 the diameter of the cutter (1/8") This base "trace" line will be will be the router guide. To simplify the travel of the router, I will use finish nails to create a fence against which the router will run. This will take very little time to make an accurate template.

I am not sure I described this well, but as soon as I create the jigs, I will post the pictures of them.

Next, I will create a similar templates for the lower rail and the end fillets. I may even do this to recut my interlocks. I am not going to worry about making the base lighter so the punchouts Joe put in to reduce weight (especially for shipping) I'll ignore.

Progress will be slow for now but hopefully methodical.

Brian G.

[Hoskald]

Very interested in seeing your progress! I am in a similar situation and may follow your lead!

Thanks for sharing!