Press Fit Hammer

[westsailpat]

Nice hammer Jake , here is another thought ... Drill a clearance hole for a screw through the hammer head and c'bore it , and thread the handle for the screw . Get it welded up and file it down and polish .

 

[Chipper5783]

This is a very good topic. I encourage you to study up on "Limits and Fits" (see Machinery Handbook). The general rule of thumb for holding reasonably well is 0.001" interference, per inch of diameter. If you get enough interference, you absolutely can get it to hold without the cross pin. We put 50,000HP though a 10" coupling (shaft size) with no keys, no splines - just a lot of interference (much attention to detail and specialty tooling).

Usually a person would bore the hole, measure it carefully and make to handle (pin) to the correct size for the fit you are looking for. You are dealing with dimensions in 0.0001" and it is easier to hit that number on an OD than it is on an ID.

With aluminum and stainless, you can probably get 0.001"-0.0015" of interference together without too much difficulty. Do you have access to liquid nitrogen? You could certainly run a little test (or do a bit of number crunching) and figure out how much shrink you can get on the aluminum. When you are doing a large shrink fit (and .0015 on a 1/2" pin is), make sure you are well set up and things go together fast (you get one chance and it last about 1 second).

Let us know how you make out, Regards, David

 

[whitmore]

... thinking about metal handles vs wood handles.
I think wood handle is more confortable due some vibration dampening but yes, metal handles look awesome and is durable.
Don't you guys who made metal handles had some harsh feeling?

I've heard this from carpenters, that steel shank and even fiberglass are
hard on the tendons. That little bit of shock that travels back up the handle
when a nail is struck... can add up. Those carpenters preferred wooden handles,
and wanted the grain of the handle to be aligned so the growth rings were parallel
to the head-t0-claw direction.

Makes sense to me (and my tennis elbow). Comforting, that Dad's old wood-handle
hammer was like new for the first fifty years, and still functional at seventy
with the original handle.

 

[Cadillac STS]

To make a piano fit through a 6 inch hole the main problem will be the iron sound board. You need something with big mass to fracture the cast iron down to pieces small enough to fit through. The small hammer is really nice but you need something bigger.

My plan would be to burn the piano as it sits to ashes and put them through the hole. Then all the smaller bits should be small enough to go. That will leave the large cast iron sound board the wires are connected to and that would take something with mass to shock and break the cast metal like a sledge hammer or some metal in that form.

 

[Cadillac STS]

Back to the press fit question and your specific hammer. Could you drill all the way through the hammer head and press fit the handle all the way through but also thread the handle and have a nut on the handle on top of the hammer head to keep it from pulling through?

 

[scwhite]

Mikey - What you are describe - the head flying off - is my worst nightmare for this project. When you say pin the head on, do you mean drilling a pin through the side of the head through the portion of the neck inside the head?

Tozguy - Any chance you could expand on what kinds of use case would make one option or the other more appropriate?

Sandia - That's a good suggestion. I wen't with aluminium for this handle because it was light (and free) but in the future maybe I will try using steel and then drilling it out to help with the weight. Would steel perform better as a press fit?

Emilio - Neither, it's a regular steel hammer with a point on one side. My school has a competition to see how quickly a (terminally damaged and irreparable) piano can be reduced to pieces small enough to fit through a 6" hole. Current students are not allowed to use traditional hand tools (sledge hammers or the like), so I am bringing a few pieces of scrap metal that happen to have been arranged in a hammer like shape (which, just to clarify, is exactly what that rule is intended to encourage).

Dulltool17 - I have been having more trouble than I would like to admit figuring out what a roll pin is via google. Do you mean these kind of things: Harbor Freight Link.

Everyone - Thank you so much for responding, I have been consistently blown away with how welcoming and helpful the Hobby-Machinist community has been (even in the face of silly questions).

At this point, it seems like there is a pretty strong consensus that pining it is the way to go. Does a 1/8th diameter brass rod seem like a reasonable option? My plan would be to sand the handle down a bit more till it will press fit in without LN2, and then insert the pin from the side through the hammer head. Not sure how to get the pins to be flush with the steel though, belt sander maybe?

Pictures as requested:
View attachment 232783View attachment 232784

What is this hammer used for