Planishin' hammer frame plan? Good/Bad?

[GTmike400]

I've been planning on building building a PHammer for sometime. I drew the frame up in AutoCAD, just wanted to run it by the pro's for approval.



Uses 10ga 2x2 Square Steel Tubing. (12 feet of it total) which I will TIG weld together.

I want something mid sized so it doesnt take over my small basement shop. Plus I wont be doing any ginormous projects on it. So, pros, cons?

[Richard K]

Mike,

Add a second horizontal strut in the rear section. They would contribute more to strength if they were connected at the point of the angle cuts in the back brace.

The long unsupported lower part is so weak compared to the rest that the back and upper bracing will make no difference; the bottom tube will bend. You need to get some suport for the bottom tube.

Why not use 4x2 tubing, double up the rear uprights and forget the bracing. I think it would be plenty strong and easy to fabricate.

Go for it!

[tdoty]

For fairly light gauge frame material, I think Richard has a good point. Take your design, and make the bottom of the frame braced like the top and have a go at it.

I take it your lower arm is going to be fixed and hold the tooling? I use a different style, the arm is adjustable - I need some pics (you might try checking out my gallery, there might be some pics in my Tools folder) - and can be offset if needed (also allows for my crappy alignment skills :shock: ). It also allows me to adjust (or even change) the lower arm to allow planishing inside a shape - just in case I ever need to planish an exhaust pipe or something !

It's a good, solid plan with the above mods. It might even be a bit of overkill - but an overbuilt tool is rarely (if ever) a problem .

Build it up, try it out!

Tim D.

[danz]

It's all about triangulation. Put every member into compression or tension by making both ends part of the corner on a triangle.

Eliminate bending forces and take advantage of the tensile strength of your material. Cantilevers, such as your lower arm want to bend. A triangle wants to keeps it's corners where you put them. HTH...

danz

[BRENT in 10-uh-C]

Maybe a dumb question but although I agree that triangulation will strengthen the framework considerable, how are all these guys that are selling unbraced units (like the ones on eBay) getting away without a rigid frame> I am sure you know the type I am talking about, the ones that look like a large letter "C" formed out of left-over exhaust tubing!

Honestly, just how 'rigid' does the frame need to be when planishing 18 gauge (+/-) sheetmetal? Tool Fabbing Guru Tim's unit did not seem to be that rigid upon close inspection at MM04.

[CCWKen]

No need to duplicate the top bracing on the bottom, if it's going to be bolted down to a bench. If you put your mounts at the front and rear of the lower boom, it won't flex much. I would eliminate the compound angles in the rear and just go with a triangle with a center brace. It'll save a little steel too.

As Brent mentions, there's an acceptable level of flex in a planishing hammer. It's not as critical as an E-Wheel. The hammer hits so fast, any harmonics will probably help move the metal. The old style fender hammers were "flimsy" compared to your design.

If you intend to use it as a "Planishing Hammer", it should work fine.

[tdoty]

My frame was also made from 1/8" wall 1 1/2" square tube Brent . For some reason I was thinking Mike was going to use 12 gauge tubing :roll: :? .

A stiffer P-hammer frame would theoretically "move more metal" based on the assumption that the hammer striking the metal between the 2 dies is all that does the work. A stiffer frame keeps the hammer from bouncing away from the work.

For my 18" throat hammer, there didn't seem to be any need for extra bracing - Chad Thomas, have you had a chance to reallly give it a workout yet? My 25" throat hammer has a bit of bracing, and doesn't really seem to need more.

If you're interested in saving some steel, and having a functional P-hammer, I don't see the need for the extra bracing. If you want a "serious looking" tool, that's also fully functional, have at it with the braces. "It looks sturdy" is a comment I often hear in regards to tools - so if you want it to look impressive, by all means build it that way .

Personally, I kind of grin at "those hammers" on eBay, Brent. I remember his old ads - "Not cheap square tubing, but strong schedule 40 steel tubing!". Ummmmmmm, square tubing is a b***h to bend - but how'd ya get that schedule 40 shaped like a C? By bending it?????????????????????????? Turn that square tube 45 degrees and it's even stiffer!

Just my opinion!

Tim D.

[tdoty]

Here's some pics of my 25" thoat hammer - and, no, I still haven't painted it . I was going to paint it before leaving for MM04 .

Here's the lower arm bracket I've mentioned several times:


This shot shows the extent of my bracing - just to take some stress off of the upper arm joint:


This last one is a shot of the whole hammer, in all it's simplistic glory :


Hope this explains a bit more of what I've been babbling about

Tim D.

[GTmike400]

My biggest problem is cost. I am saving up for a TIG welder, but in the mean time Im using a buddies TIG, and the Schools MIG.

I dont want to spend tons and tons of cash. I just want it to be a quick cheap project to smooth out all the bumps I put in the material with a hammer.

I also have a tough time locating steel. I can probably find a little bit of 2x2 but probably not much, without costing an arm and a leg. So I am trying to save up on steel. I'll post up another plan in a few that might save some steel.

I appreciate all your comments and suggestions and heeded them greatly.

[Steve Hamilton]

Hi Guys

I'm not an expert, but have used a number of planishing hammers over the past 8 to 10 years. I think that the frame strength is not as big of a factor with the planishing hammer asit is with an E wheel.

The E wheel frame is what is appying the force to the metal to thin or to smooth it. A constant applied force.

The planishing hammer frame is just holding the hammer. the hammer is applying the energy to thin or smooth the metal.

For stretching metal with a planishing hammer a loose die adjustment (more hammer travel) and higher air pressure, will get the job done faster. For planishing (smoothing & leveling) dies need to be tight to the metal, and the air pressure reduced.

Remember there are two types of planishing hammers. those that have a fixed frame and the hammer does all the work. Here the frame strength is not as important. the second type the operator controls the applied pressure by a hand or foot control. Now the frame strength is more a factor. With the second design more strength in the frame (from my experience) makes the planishing (smoothing) go faster.


So design for what you will use it for

Steve Hamilton