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  #21  
Old 04-22-2012, 07:00 PM
grenwis grenwis is offline
 
Join Date: Feb 2005
Location: Arvada, CO
Posts: 39
Default Another Harbor Freight Jack

I built a jack like this using the great ideas I read about here. Thanks to all you experts! I used 3/8" all-thread at the top for connection of the jack to the wing. I put a lock nut on either side of a gas line cap, then ground off the threads inside the cap to make the end of the all-thread smaller where it would fit into the top of the jack. The gas line cap is probably not needed, but I felt better with captivating the assembly over the top of the jack.

At the bottom of the jack I added one thing I hadn't seen here. I was concerned that the bottom of the jack might slip out and allow it to fall over. I used a jigsaw to cut out the shape of the bottom of the jack in 3/4" plywood. I bolted that piece of wood to the larger bottom support using bolts up from the bottom. The jack does not have any bolt holes to allow directly mounting it so this method traps the jack in the cutout area of the second piece of wood. Now the jack is secure at the bottom along with the supports at the top as shown by others. I used double hose clamps to increase the strength there. Pictures follow.








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  #22  
Old 04-22-2012, 07:04 PM
Greg Arehart's Avatar
Greg Arehart Greg Arehart is offline
 
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Location: Delta, CO/Atlin, BC
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Default

FWIW, I drilled holes in the base of the jack and bolted it down. I like the welded versions a lot, but have zero welding skills.

Greg
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  #23  
Old 04-22-2012, 07:27 PM
gtmule gtmule is offline
 
Join Date: Oct 2007
Location: Macon, GA
Posts: 499
Default

Seems like the shorter, $18 bottle jacks would work just as well, assuming you made a taller stand. Any reason why not? I'd think 6" of lift would be more than enough?

http://www.harborfreight.com/4-ton-h...ack-66450.html
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  #24  
Old 04-23-2012, 05:06 AM
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pierre smith pierre smith is offline
 
Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
Default Really cheap.

Mine are simply two concrete blocks with a flat piece of wood on top, then the usual bottle jack borrowed from my bench press.

Fred Flintstone kinda deal! Jack both my -6A and -10 with them.

Best,
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  #25  
Old 04-23-2012, 07:24 AM
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Greg Arehart Greg Arehart is offline
 
Join Date: Jul 2007
Location: Delta, CO/Atlin, BC
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Default

Quote:
Originally Posted by gtmule View Post
Seems like the shorter, $18 bottle jacks would work just as well, assuming you made a taller stand. Any reason why not? I'd think 6" of lift would be more than enough?

http://www.harborfreight.com/4-ton-h...ack-66450.html
I have two of the shorter bottle jacks and, yes, they work but barely. There's a lot of spring in those legs. MUCH more convenient to have the longer throw and not require boxes or cinder blocks etc. underneath. In addition, when I change from small to large wheels/tires, the smaller jacks were not sufficient (probably not a lot of others out there doing that though!).

Greg
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  #26  
Old 04-23-2012, 07:35 AM
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schristo@mac.com schristo@mac.com is offline
 
Join Date: Sep 2007
Location: WA
Posts: 988
Default resistance to overturning...

Beware of using a small jack on blocks, there is not much resistance to overturning with a small jack fully extended... It takes a surprising length of extension to get the wheel in the air and there is some positional movement of the jack point, especially with a tail dragger with the the tail on the ground.

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  #27  
Old 05-15-2012, 03:21 AM
GusRV8 GusRV8 is offline
 
Join Date: Mar 2009
Location: Virginia
Posts: 37
Default Jacks are...

$40 online right now. Might have to do this just as a side project, or to at least have the jacks handy for future use.
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  #28  
Old 05-15-2012, 06:30 AM
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Jimboscr Jimboscr is offline
 
Join Date: Jan 2011
Location: Adelaide South Australia, Australia
Posts: 193
Default

From the number of people doing it I guess it is o.k. but are the two tiedown points strong enough to support the weight of the whole aircraft?

Quote:
Originally Posted by Mike S View Post
I built these a year + ago, have worked well for me.

I welded the jacks to steel plate, about 14" square, 3/8" thick.

Bit heavier than the ones shown at the start of the thread, but totally no way they are going to tip over in normal use.

Mike I see in your Picture you are jacking from a fueslage point near the undercarrage. Exactly where is that point?

Jim
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  #29  
Old 05-15-2012, 07:36 AM
koda2 koda2 is offline
 
Join Date: Mar 2007
Location: West Texas
Posts: 282
Default Jack stands

The idea has been around for a while ever since Harbor Freight has had the cylinder jacks available at a reasonable price.

I made these eight years ago, for use in certified aircraft that were significantly heavier than RVs. A little over the top but they will probably last as long as the cylinders will hold up.



One accessory I did not add was some small casters on one end so that the stand can be tilted slightly and then rolled under the wing. They are pretty heavy to drag around.

Dave A.
6A build
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  #30  
Old 05-25-2012, 09:17 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
 
Join Date: Jan 2005
Posts: 3,646
Default

This is probably a dumb question, but although I know jacking at the tie down point is common, is the tie down point strong enough to hold +/- 500# of plane all in that one point on regular basis? Usually it's one bolt on the jack going into the tapped extruded aluminum tie down bracket which, in turn is attached to the spar with nothing more than 4 AN3 bolts. Seems like a failure either in the treads, bolt, tie down bracket, and/or spar would be quite problematic. Just curious.
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