For Scratch-builders...20 Ton Press/ 20 Ton Air/Hyd Jack on Sale at HF This Week

[SpruceForest]

For those forming ribs with the press or hybrid methods, the 20 ton press and jack setup from Harbor Freight does a great job, and is on sale thru at least the next week as part of HF's extended parking lot sale. With the coupons out this week, $309 for press and jack ... need to add two 3/4" x 12" x 12" hot or cold rolled steel plates ($103 off eBay or less at a scrapyard), a 1" x 12" x 12" urethane pad ($157 at McM-C), and some 3/4" stall mat ($53 for a 4' x 6' piece of the heavy stuff at tractor Supply) to build out the rest of the package. With tax and shipping figure on about $700 total for the complete setup. Ouch, but here's what to expect with press:

- Nose ribs press out with minimal distortion that clears once fluted
- Aileron and flap ribs press in one shot including joggles with no need to flute or straighten; all the small stuff (aileron and flap nose and pocket ribs) press out without much more than final tweaks on the pocket rib joggles
- Center and tip rib lightening holes press out without any distortion (I flow and hammer-formed the edge flanges on - other than the nose and trailing edge portions of the tip ribs - because it was just too many cycles of the press to get through a rib and the joggles needed to be touched up in any case)

Will keep my press for the usual steel-forming stuff, but wrapped up my stacks of Patrol ribs (160 total... 80 in the wing, 80 in flaps and ailerons) with the milling of the leading edge holes on the aileron nose ribs yesterday. Whoo-hoo! Plastic still on in the shots...

160_Wing_Ribs_Done_Aug22.jpg

[Bcone1381]

I spent a year of shop time forming ribs in 2015. A series of events (a death, a conflict between skill level and standards, recognition of a truthful time line for me) led me to abort wing building and buy kit from Mark. I still follow plans builders techniques hungry to understand the best practices for us (them).

Folks, Rubber Pressing the ribs like Spruce describes is an Industry Best Practice. Like he says, You need a significant press, the steel and rubber to do it right. Buy these tools and materials, press them out, then if $ is short, sell the items here in Classifieds when you are done.

[Rob]

Would you have a part number for the urethane pad you used?
Thanks

[Chris In Milwaukee]

I concur with all of the above! The best thing the hydroforming did was avoid majority potato-chipping of the workpiece. Definitely a bonus!

[SpruceForest]

John Snapp (aka N3UW) recommended McMaster-Carr PN 8789K81, Abrasion-Resistant Polyurethane Rubber Sheet, Amber, 12" x 12", 1" Thick, 60A hardness, and that was a really good call on his part.

The stack I used was the 1" urethane on top, a piece of 3/8" neoprene beneath it, then four pieces of stall matting, then the bottom 3/4" press plate. The top press plate was also 3/4" hot rolled material suspended by 1/4" carriage bolts from the press crossbar (this avoids rebuilding the stack at each press... you don't want the part on the bottom of the stack). The urethane rubber was very durable (will likely hang on to mine for the next project!). I also used a piece of .375" x 12" x 12" neoprene between the stall matting and the urethane, but in retrospect, I don't think it really did much of anything.

The stall matting I used was sourced from Tractor Supply, and it is a good thing it comes in a 4' x 6' piece (to yield 24 12" x 12" pieces), as the center laminates eventually begin to fracture and need to be rotated out... I think I have 8-10 unused pieces left, plus the four in the current stack (no fractures yet).

Tractor Supply SKU: 221900399, 4 ft. x 6 ft. Thick Rubber Stall Mat.

This stuff is 100% recycled, re-Vulcanized rubber, so is fairly tough, but eventually fails at the edges. That said, a single mat at about $55 will handle at least a full project's worth of press work, and compared to an additional two- pieces of the McMaster-Carr material at about $170 delivered per piece, it is a bargain. FWIW, the stall matting has raised areas on it to allow wash down, but that really does not interfere with our use. Any 3/4" or 1/2" stall mat material would likely work, providing there is about a 4" total depth of stack on the press pad (1" urethane plus 3" stall matting). When I reduced the stack thickness below 3", I saw a bit less flange angle (60 deg versus 70-75 deg), which made flange straightening a lot less certain with regard to maintaining the correct contour. I did not see any benefit in adding another inch of stack thickness (5" plus that bit of neoprene), so went back to 4" total (plus neoprene).

Misc. Stuff:

- The stall matting cuts with a utility knife...resist the temptation to run it through bandsaw or table saw...the mess is a pain and knife-cutting is just way easier. A 48" aluminum yardstick and a scrap of 1/4" ply keeps the cuts straight and off the concrete.

- Always make sure the MDF form is on the top of the stack... the aluminum has to be next to the urethane. Messing up and getting the aluminum on top of the form pushes the steel alignment pins into the aluminum... bad idea.

I am doing a final set of revisions to the doc on forming wing ribs back in May... will post the updated version soon once I get a clean version. I am adding joggling info and some of that "...in retrospect,..." stuff, plus a table on the forms and templates used.

[SpruceForest]

Here's the updated Forming Wing Aileron Flap Ribs V2.1.pdf doc... also includes a table of the templates and forms needed for the approach.

[rcraddock]

I picked up a press from HF this morning, thanks for the heads up. Since I cheated and bought ribs and spar webs from Mark, I plan to use the press with a Swag Off-road finger brake add on to bend brackets and such.

[SpruceForest]

I picked up a press from HF this morning, thanks for the heads up. Since I cheated and bought ribs and spar webs from Mark, I plan to use the press with a Swag Off-road finger brake add on to bend brackets and such.

Not cheating...just some of us are slow learners on the 'time versus money' thing.

Had not seen one of those... was thinking about drawing one up, but all the work is done... perfect! Thanks!

[sjt]

I copied John Snapp also,

I used the 20 ton press for lots of stuff in addition to ribs.

I found a source for 1 inch think mdf for making ribs



bending 4130 brackets
one.jpg
two.jpg





Hold down rib while forming edge over mdf.

p.s. the orange hammer comes from harbor freight.

amber.jpg

[rcraddock]

Those are the brackets I have in mind, thanks for the pic.

[Chris In Milwaukee]

And also highly recommend the air-over-hydraulic jack upgrade.

[Rob]

Thanks for taking the time for the detailed description.