Convert Harbor Freight 20 ton press to 32 ton

[Steve]

I wouldn't use grade 8 bolts for support pins because the harder steel will shear instantly rather than bend or deform. A grade 5 bolt is a better choice for shear stress.

That is an interesting comment.

I did a bit of research and before I made my decision, I needed to know the shear strength of a grade 5 and a grade 8 bolt at 1 inch thick.

Here is what I found according to Mark's standard Handbook for Mechanical Engineers:
Here is the link: http://www.rockcrawler.com/techrepor...ners/index.asp


A one inch grade 5 bolt shears at 58,900 lbs.

A one inch grade 8 bolt shears at 71,500 lbs.

The surface area where the bolts will contact the side of the frame has been doubled with the addition of 1 inch grade 8 washers welded to the supports on each hole. Each pin or bolt would have two contact points each for a total of four contact points with the frame. So each contact point would have at least 14,725 lbs on them. But, the tops of the pins will have no pressure so you would have to increase the pressure on each of the points to about 17,600 lbs on each contact.

So, yes I could have used grade 5 bolts and it would have a very good safety factor.

Each grade 8 bolt has a shear strength each that is at about the capacity of my hydraulic jack. Just one bolt alone!
The safety factor in having 4 contact points (which has been increased in surface area) is way more than I would ever need. The grade 8 bolt has 12,600 lbs of more shear capacity (over 6 tons) over the grade 5 bolt.

I highly doubt that I could ever break these bolts with the setup I have. But I agree, a grade 5 bolt would have saved me some cash and would have been just fine for my use.

I may in the future go with a 50 ton air hydraulic set up. The grade 8 bolts would still be fine for that. The only thing that I would have to worry about is the frame which could be a problem. I am going to eventually install tubing inside the C channel and also add 5/16 plate to box the frame in for even more strength. I want to do some hole punching and a 50 ton press would really be the cat's butt!

[zoama]

That is an interesting comment.

I did a bit of research and before I made my decision, I needed to know the shear strength of a grade 5 and a grade 8 bolt at 1 inch thick.

Here is what I found according to Mark's standard Handbook for Mechanical Engineers:
Here is the link: http://www.rockcrawler.com/techrepor...ners/index.asp


A one inch grade 5 bolt shears at 58,900 lbs.

A one inch grade 8 bolt shears at 71,500 lbs.

The surface area where the bolts will contact the side of the frame has been doubled with the addition of 1 inch grade 8 washers welded to the supports on each hole. Each pin or bolt would have two contact points each for a total of four contact points with the frame. So each contact point would have at least 14,725 lbs on them. But, the tops of the pins will have no pressure so you would have to increase the pressure on each of the points to about 17,600 lbs on each contact.

So, yes I could have used grade 5 bolts and it would have a very good safety factor.

Each grade 8 bolt has a shear strength each that is at about the capacity of my hydraulic jack. Just one bolt alone!
The safety factor in having 4 contact points (which has been increased in surface area) is way more than I would ever need. The grade 8 bolt has 12,600 lbs of more shear capacity (over 6 tons)

I highly doubt that I could ever break these bolts with the setup I have. But I agree, a grade 5 bolt would have saved me some cash and would have been just fine for my use.

I may in the future go with a 50 ton air hydraulic set up. The grade 8 bolts would still be fine for that. The only thing that I would have to worry about is the frame which could be a problem. I am going to eventually install tubing inside the C channel and also add 5/16 plate to box the frame in for even more strength. I want to do some hole punching and a 50 ton press would really be the cat's butt!

You want it to fail slowly if it fails. A grade 5 will deform a little before it shears or bend before it breaks. As long as you're happy with it that's all that counts.

[MuttonHawg]

Perhaps a stupid question, but considering how much you've modified this press reinforce it, do you have an estimate for how much more/less it would've cost to just build your own? Plus, then you could design the dimensions (wider, for instance) to whatever you'd need rather than be constrained by the dimensions of the existing press.

Or, posing the question another way: having gone through this process, would you consider building your own, or stick with the reinforcement of an existing HF press?

[Steve]

Perhaps a stupid question, but considering how much you've modified this press reinforce it, do you have an estimate for how much more/less it would've cost to just build your own? Plus, then you could design the dimensions (wider, for instance) to whatever you'd need rather than be constrained by the dimensions of the existing press.

Or, posing the question another way: having gone through this process, would you consider building your own, or stick with the reinforcement of an existing HF press?

Not a stupid question at all!

I did do some calculations on getting all the metal and building from scratch. Scratch would be about 30% more than getting a Harbor Freight 20 ton and modifying it. I got a really good deal on the HF press, $149 out the door. My local HF is just a few miles away. The closest metal store is 45 miles away. So I saved on gas. I had scrap metal laying around from other projects and so the cost of all the extra metal was not an issue. I also got a pretty good deal on the air /hydraulic jack on E-bay with a 15% off coupon. That cost me $132 with free shipping.

The design of the HF press is a pretty standard design and it does have some pretty good strength to it. With all the changes, I almost doubled the weight of the press and was able to use up a lot of scrap steel laying around and put it to use. Most of the work on the press was already done. Holes just needed to be widened from .75 to 1. And then just adding metal to the places that need it. I've never really needed anything wider than 22 inches so the HF press works for me. I had a 25 ton press and it sometimes was a bit less than what was needed. The new jack is actually rated at 35.2 tons or 70,400 lbs. .

I guess it comes down to circumstances. I was needing a new press. Harbor Freight had a sale on theirs. I saw the 32 ton jack on E-bay and had a 15% off coupon. I had lots of leftover steel. If any one of those things did not happen, I probably would have just built one from scratch. But then again, I'm pretty happy with what it has become so I think I made the right choice in modifying the 20 ton.

[Rambozo]

HF has quite a few things that sell for less than the cost of the metal, at least when on sale, coupons, etc. However, even the steel is rather sub par, and often will need reinforcement to operate as described. I look at it as building a kit. If you are willing to add a little sweat equity, then you can end up with something pretty nice for what you need. If you expect things to be turn-key ready to work, you are dreaming, or just lucky.

Nice job on the press there. I would probably do something similar, but can't justify the space at the moment.

[everlastsupport]

Nice job on the press there. I would probably do something similar, but can't justify the space at the moment.

I have two and both are outside undercover at both locations. One is Everlast green other just old and big and rusty. For the space and the amount of uses, they are hard to justify for me. Not easy to move either.

[Steve]

I think I am pretty much done with the Harbor Freight mod to make it a 36 ton press. I did reinforce the side rails and added schedule 40 tubing into the holes which I expanded to 1 inch for the 1 inch x 14 inch grade 8 bolts for the bed pins.

I also added wheels to the base as the thing was getting pretty heavy and was hard to push and was marking up the floor. I upgraded the angle iron that was the legs to a thicker version for added strength. The wheels are rated at 250 lbs each. The weight of this thing now probably a bit over double what it weighed bone stock.

I also added some grips to the bed to make it a little easier to move it up and down. The bed now weighs in at 87 lbs. as I have reinforced it with 5/16 inch plate on both sides.

Here are the final photos:

I really like this press now. The Harbor Freight press is pretty nice as is especially when you get it for under $150. I needed a bit bigger press but the ones available were way too high price wise. I could have built one from scratch but when the HF press went on sale, I could not resist and saw a chance to make it even better. Plus it was fun modifying it to make it do what I needed it to do!

[Rambozo]

Not much HF left in there.

Reminds me of something another mechanic used to say about some cars. "You just need to jack up the radiator cap and install a new car under it."

[Steve]

Not much HF left in there.

Reminds me of something another mechanic used to say about some cars. "You just need to jack up the radiator cap and install a new car under it."

Ha! That is pretty much true. The only thing left is the side rails, the top and some of the bottom.

I've probably got a little over $500 in this 35 ton but to get one like it new would cost quite a bit more than that. I know Harbor Freight has a 50 ton for $699 but it is pretty big and it looks like it is begging to be modified!

[everlastsupport]

Not much HF left in there.

Reminds me of something another mechanic used to say about some cars. "You just need to jack up the radiator cap and install a new car under it."

I heard it as jack up the wipers when I heard it from an old mechanic.

Looks like his press will hold up. It takes 2-3 people to move mine. Wheel might be in order.

[DVA]

Not much HF left in there.

Reminds me of something another mechanic used to say about some cars. "You just need to jack up the radiator cap and install a new car under it."

That is a good one. I may need to borrow that line from time to time.

[ShaneJackson]

Not much HF left in there.

Reminds me of something another mechanic used to say about some cars. "You just need to jack up the radiator cap and install a new car under it."

LOL that is too funny. I agree it does not look like a HF press at all now. I have one sitting in the corner... I may have to upgrade it.....

[youngnstudly]

Wow, I didn't realize all that you did on this press to convert it! I must have missed reading a portion of your post regarding the bad MIG wire, or it didn't register with me! Do you send your items out to be powder coated and sand blasted, or is this a setup you have in a shop that allows you to do the work yourself?

That Swag Offroad brake kit is very nice for turning your standard press into a very capable metal brake! That site has some other very useful DIY home fabricator type projects as well. I've had my eye on a few of their shop tools for a while.

[Steve]

Hello Andy. I do my own sand blasting. I have a source for powder coating but I rarely use it. I prefer paint as powder coating when damaged is a pain to fix.

All my work is done in either my basement or garage. I do build things to sell and it helps pay the bills and keeps me out of trouble.

Yeah, I had some Harbor Freight mig wire and it gave me all kinds of trouble. So I scrapped all the mig wire I had from them and use only Lincoln, Hobart or my local welding store brand which I prefer over them all. I only use the Lincoln or Hobart if I run out of wire on a weekend and so Home Depot or Tractor Supply gets a little business.

[youngnstudly]

Hello Andy. I do my own sand blasting. I have a source for powder coating but I rarely use it. I prefer paint as powder coating when damaged is a pain to fix.

All my work is done in either my basement or garage. I do build things to sell and it helps pay the bills and keeps me out of trouble.

Yeah, I had some Harbor Freight mig wire and it gave me all kinds of trouble. So I scrapped all the mig wire I had from them and use only Lincoln, Hobart or my local welding store brand which I prefer over them all. I only use the Lincoln or Hobart if I run out of wire on a weekend and so Home Depot or Tractor Supply gets a little business.

That's very cool! I would like to build a large bead blast cabinet one day that would allow larger items to be blasted in a contained area. Sand blasting can get a little messy, and the current cabinet I use is just big enough for two 16" automotive rims to fit inside of.

I used to be involved in building things to sell (back when I was working and going to trade school) as I too needed the extra money. I always found that working on even small projects keeps your mind sharp and you out of trouble!

The money that some people spend at the local bar on Friday nights ($200 or more!) is enough to keep me hobbying on projects for quite a while...plus I'd rather be hit in the face by the project I'm working on, as opposed to some big, mean, drunk guy punching me while I'm sitting there minding my own business! At least the project can claim that it was using self defense while I hammered on it!

[everlastsupport]

Steve,

It looks good.

Air over, if you use it a lot, is a nice feature. I used mine the other day and I am sure I pumped the jack at least 100 times if not more.

[Steve]

Steve,

It looks good.

Air over, if you use it a lot, is a nice feature. I used mine the other day and I am sure I pumped the jack at least 100 times if not more.

Thanks!

I posted this to show how a fairly good hydraulic press can be made into a great press. There is a lot of information and reviews on the Harbor Freight 20 ton press, but very little on how to make it better. I've always been involved in modifying cars, computers and other stuff to make it better and this was a perfect project for me.

Now I have a problem. I am looking for stuff to squash and bend!

[Steve]

It's been a little while since I modded my Harbor Freight 20 ton and made it into a 35 ton press. I can report that the mods have made this press a very useful tool that I have used quite a bit lately. I would recommend to anyone that even if you don't reinforce your Harbor Freight press, at least get the air over hydraulic bottle jack for it. They have some pretty good deals on 20 ton air hydraulic bottle jacks on E-bay. My old press was hand pumped and I hated using it as it took so long and took a lot of effort to make it work. The air bottle jack makes it a really nice tool to use. I also recommend putting some wheels on it. Moving it around is now so much nicer now that it has wheels.

I've been bending a lot of 10 inch wide half inch thick plate with it and I highly recommend heating any metal past 3/8 inch thick. I bent the Swag Off Road brake while bending half inch. The base of the brake got squashed and the whole brake bottom bent. The hydraulic press did not even notice! It was fairly easy to fix with the new 35 ton press and I also reinforced the Swag Off Road Brake with a thick piece of angle on the base, effectively doubling the thickness and preventing any more bending. But I have noticed stress cracking on metal I am bending that is thicker than 3/8 inch. So I heat it up with the torch and then bend and that solved the stress cracking. Plus it is less stress on the press and brake. I just have to remember not to grab the metal!

Overall I would say that if you have the need for a great press, the Harbor Freight 20 ton press with modifications is the way to go. Their 50 ton press is almost $600 and has some issues that make it too big for a lot of folks. The 20 ton with the 35 ton mods makes it a press that fits in the same space as the 20 ton while giving 99.9% of the performance of a larger tonnage press. Plus it is a whole lot of fun modifying it and then testing on bowling balls and golf balls.

[Steve]

I did one other modification yesterday. Went to the metal store and got some C channel and build a new jack carriage. The factory carriage was not too good with rather poor welds and the pressure pin was not too straight which ended up putting some lateral pressure on the frame. So I also got a 1.5 inch diameter 8 inch grade 8 bolt and cut off the threads and used that as a pressure pin.

I also bent some 1/4 inch x 2 inch plate and made some guide straps for the carriage and bolted them to the carriage with 1/2 inch grade 8 bolts. That SWAG press brake works pretty good! I then added a 5/16 inch plate under the jack for better support and also built a valve wrench out of small tubing.

Today I will also add some 1 inch schedule 40 pipe to the pin holes and then weld 1/4 inch plate to the main frame C channel to box it in.
I'm doing that to in the future be able to use a 50 ton air hydraulic jack or maybe a pure hydraulic motorized drive.

In the future, I will probably put some wheels on it instead of bolting it to the floor. I found it to be pretty stable as is but I do see the need to wheel it around.

Here are some recent photos of the new carriage.