Re: Aluminum frame with steel beam

I have little experience with welding aluminum. I was reading about how to calculate strength of aluminum welds and found that welding weakens aluminum. The weld itself is OK but the heat anneals the temper out of the metal and so softens (weakens) it up. Some products get re-heat treated after welding to toughen them back up.

I've designed many tools and small machines but for this kind of "back yard" engineering I would guess how heavy it needs to be... Then make it heavier!

Do you know what material/temper you have?

I want to see photos of your build. (With or without cracks) ---KenA

 

Re: Aluminum frame with steel beam

i agree that there would be alot of stress on those welds, but there would also be alot of surface area to weld.. first, I would weld the 6" top piece across the tops of the side members. Then weld a 3/8" plate on the front and back overtop of the point where the sided meets the top and weld the plate on all sides.
to hold the stress at the bottom i think i would go with the idea of drilling holes in the aluminum sides but also adding perhaps a 1/4" steel flatbar, with holes drilled to match the frame placed over the frame to avoid stretching the holes in the aluminum.

if i am near the scrapyard where i buy some used metal (out of my way an hour) I may see if they have any steel that would be well suited, but much cheaper than new steel.

 

Aluminum frame with steel beam

If I understand your thinking... there would be a 6" sq. aluminum frame with added heavy steel plate for top beam where the load is concentrated. I suppose you could make that work somehow BUT the trick would be the attachments. Somehow the force must be transfered from the steel beam directly into the vertical aluminum sides. This is getting into tricky design / calculating stuff beyond my level. How strong is that aluminum weld ??? Hummm.. --- KenA

 

yes, plate steel bolted on may be an option to reduce wear.

Ken - I like the design of that one.. if I did use aluminum I would I could put something like a 12" High plate of 1=3/8" across the top, in front and back of the frame to give it much more rigidity. even for cross members, I could use 10-12 " high plate on the front and back to keep it rigid.
I know steel would be better and more compact.. just seeing if what I have for free will work. if its totally not worth it, then I won't attempt it... or I will just buy steel for the parts I need.

 

Princess Auto has them https://www.princessauto.com/20-ton-hydraulic-bottle-jack-shop-press/product/PA0009193798

 

Build your own (with steel)

Building a shop press is a fun project and you can end up with a more rigid frame than the (cheap) purchased variety. Aluminum uprights might work (in tension) but the cross members are a problem. I would choose steel as the frame would be more compact.

If building your own press you don't have to copy the store bought ones. This is a 12 ton (tested for 20 ton) press I put togeather last year. 3.5" pipe with 2.5" sq cross members. Top cross member also has a 2" sq tube inserted. This eliminated all the drilling. The ram has no play like the channel versions. The guide bar was wood to start but had to be changed to steel because of side loads. This was an early photo. I built this with old pipe and other steel I had laying around. I had a 12 ton jack. My total investment was $12.
View attachment press-1.jpg

 

Lis2323 - very cool solution to the no drill uprights.
seriously heavy duty.

 

yes, I wondered how bad the holes might stretch. I have lots of 3/8" plate, so I could easily run a piece of plate down the front and back of the uprights, so it would now be the 1/4" tube plus the 3/8" plate where the holes are drilled...that should help to reduce hole stretching, but not sure if it still would be acceptable.. this is for occasional use, pressing bearings in for an antique tractor, etc.. where I can build it for zero dollars I am tempted to try... the cheap Princess Auto model still costs $265 including taxes..

 

40 years ago I didn’t own a mag drill ( probably didn’t even know they existed).

This is what I did for “no drill” uprights.

View attachment IMG_3257.jpg

View attachment IMG_3254.jpg

 

hi Alan - i just took a guess at the 36" opening... really just want similar dimensions to the harbour freight ones.
thanks for providing the details on your model as well as the comparison to what it would be like in aluminum!
i think it is likely 6061

 

If you are looking for a fun project, why not?

36" is pretty wide for 20 ton press. I have a Strongway with a 21" bed opening that is similar to the Harborfreight version, but uses a ram instead of a bottle jack. This press let me get the Swage Offroad press brake and cut it down 1" to fit. Anyway, this press is made using 4" channel stock. I'm not sure on dimensions but could measure it in more detail if you are interested.

6" tube with with 1/4" walls has a substantial section increase from a 4" channel. This will help offset the ~2/3 loss in stiffness you see when shifting from steel to aluminum.

So comparing to the press I got from North Tool, your 6" square tube would be less than 1/3 as stiff if you used a 36" opening. If you cut your opening down to about 23" you could expect similar stiffness.

Do you know what alloy your aluminum is? Probably a 6xxx series?

Also, note that aluminum fatigues differently than steel so you will need to put careful thought into where you put your welds.

Cheers, Alan

 

thanks for all of the advice. we do have reasonably priced ones at Princess Auto here, similar to Harbour Freight.
I am one of the few guys around here who weld aluminum as a hobby, so not much chance of selling the aluminum i have leftover for anything but scrap prices.
if it would have been ok to use i would have enjoyed building it, and l already have an extra 20 t jack so for me it would have been cheaper to build. the aluminum would have been much nicer to drill as well...
New steel prices are insane now so I agree it is cheaper to buy than to build if i need to buy new steel.
i can find some good scrap prices on steel but it usually on heavier pieces which would be overkill for this, so I may just buy a cheap one.

 

. the aluminum would have been much nicer to drill as well...
.

Keep in mind the holes in aluminum would also stretch or wallow quickly.

 

Another no for the aluminum.

If you only require 20 ton it will be way cheaper to buy than build.

Thomas made a good suggestion in post #4.

 

Another no for the aluminum.

If you only require 20 ton it will be way cheaper to buy than build.

Thomas made a good suggestion in post #4.

Except for the fact that the OP is in Nova Scotia, and I doubt there's a Harbor Freight outlet there.

 

View attachment IMG_6095.jpg This will fill simple 20k. Needs. https://www.harborfreight.com/20-ton-h-frame-floor-shop-press-70603.html Install some casters on it to move around the shop.

It is cheap

 

hi Folks - I have been thinking about building a DIY shop press, likely about 20Ton.
Before I go out and pay too much for new steel to build it, do you think that a frame built out of 6 inch square aluminum tubing (1/4 inch or more thick), with additional 3/8 inch plate at the top / gussetting would be strong enough?
I have the scrap aluminum laying around....
I know aluminum is strong for it's weight, but it is more flexible..so would a frame with those materials flex enough to make the press much less efficient?

planning on a floor model, so sides perhaps 4-5 ft high.

thanks in advance!

note. I tried an on-line calculator with a 40000lb load and a 3 ft length and changed the materials from steel to 6061 Al and the safety factor only changed from 1.28 to 1.4 but I am far from an engineer... but I would like some opinions please. with 1.4 safety factor being for the aluminum being higher, I think that means safer.. but will it flex too much..

Another thought... even if the frame was strong enough, would the moveable pins holding the adjustable plates / brackets that you move up and down on the front and back cause the holes to elongate with the pressure from the press - thinking of having maybe two 3/4 inch pins/bolts holding the plates on each side... so these pins going through the plate and the tube frame would have to hold the weight of the push...

Can you trade the aluminum for steel more appropriate to the task? Maybe more common I/H beams? Lots of proven designs that would be easy to copy using steel. Or build and sell something from the aluminum and then buy what you'd like?

Do you have any useful websites like Craigslist there that might work for finding such a trade?

 

No on the al.