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I Forge Iron

Handle woes, metal wedge too big?


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So this is the third time this year I've snapped this hammer's handle. I'm very much a weekend forger, and the longest time I've had between snappage was probably about 10 forging sessions of a few hours each. It's my favorite hammer head at the 16oz size so I'd like to get this right. I'm gonna give you all the details if any of you feel inclined to post-mortem where I went astray.

First break:
For the handle, I took a concrete tamper and cut a chunk off the handle. It was labeled as and ash handle, but who knows. I cut a slot for a wooden wedge on the band saw, drove a wooden wedge and a metal wedge in. I've made all my own wooden wedges using shim scrap and a palm sander. The wooden wedge went with the long axis of the eye, and I put the metal wedge at a 45 to the wooden wedge. After driving the metal wedge, I saw a crack about 3/4" long running down the length of the handle starting where the eye touches the handle. I filled it with epoxy and forged away. Lasted quite a while, but broke after about 10 forging sessions with a jagged fracture under the eye. I didn't get any photos of this break.

Second break:
While rehandling after the first break, the handle snapped on a diagonal plane while I was driving in the metal wedge. I just took the first handle, cut off the snapped part and rasp-ed the end down to fit in the eye, and cut a slot for a wooden wedge with a borrowed dozuki (it's not mine, I'm not one of those guys, I swear! :P). This time I used linseed oil on the part of the handle inside the eye and on the wood wedge after researching the forums here. This time I took a photo:

IMG_20201111_095109.jpg.2bf9a8704e8c382608f4e82f6faba6db.jpg

Looks to me like the metal wedge was too much stress and caused a crack or propagated what was left of the crack on the first attempt.

Third break:
I ran out of tamper handle, so I dug through my box of saw drops and found a piece of kiln-dried plane-sawn that was so white it had to be ash or maple. As I'm writing this and looking at the rest of that wood, it doesn't have the grain to be ash and I'm pretty sure it's maple. I shaped the handle on my belt sander, and did the same procedure as the previous two times, wood and metal wedges. I didn't see any cracks on the wood after driving the metal wedge. Two forging sessions later, the head flies off. I have pictures, but I'm pretty confident I just solved this one by realizing I used maple instead of ash.

Overall, the common denominator of the first two failures seems to be the metal wedge, and the third was a material mistake. The wedge is about 1/8" thick by 5/16" long at the widest and tapers over 5/8" ish, with three "barbs". The hammer eye is very roughly 3/4" x 1/2". When I use no metal wedge, the wood wedge always starts backing itself out after the first few strikes (both for band saw cut slot and dozuki cut slot). I haven't tried waiting long enough for the linseed oil to set before swinging, but I feel like the wood wedge shouldn't back itself out that easily linseed or no. Any advice here?

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Make and cut a slot for the wedge that has a bit of a kerf.  Smear the sides of the wooden wedge with wood glue to make the wedge slide into place easier.  Once the glue sets, the wedge should stay put.  If it later loosens up, add a metal wedge.

When you finish putting the handle into the hammer head, leave 1/4 inch of the handle sticking out of the hammer head.  This will mushroom over in time and keep the head from coming off the handle.  Turn the hammer handle up in a bit of boiled linseed oil and mineral spirits and let the mixture soak into the wood. Couple of days should do, and add more mix as needed to keep the wood covered.   Remove the hammer and wipe the hammer head as well as the whole hammer handle using the mix and an old t-shirt.  When finished burn or spread out the shirt material so it does not spontaneously combust.  Wipe the handle with the boiled linseed oil and mineral spirits mix every day for a week and once a week for a month.  Let the wood suck up all the mix it wants.

Examine your hammer technique.  You can not push the hammer to move metal, so hold the hammer loosely let the hammer head do the work.  When it wants to bounce off the metal, let it, catch it on the way up and swing again.

Others will have additional suggestions.

 

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Watch the grain!  If the grain is running correctly you might get a handle that splits in two all the way from the head to the end of the handle; but it shouldn't break across like that one.  When I buy handles I check the grain on every one I buy; I've found a lot of bad ones being sold over the years!

Instead of a tamper I'd look for an axe handle or pickax handle as they are tools design to be swung with impact at the end of the swing.  BUT check the grain on those as well!

When trying to find local woods to use as handles we generally suggest checking out what the indigenous peoples used to make bows from.

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Thanks all for the replies, learned a bunch.

So, from the sounds of things, I need to get my hands on some better materials, for starters. Irondragon, baseball bats were a great idea but I checked the old craigslist in my area and everyone's got aluminum bats, and I don't think there are going to be many yard sales what with 1 in 10 people having the rona around here. Maybe when it gets warmer I can try that. I do have an old maul, might chop that up if I have no better options. I checked my wood scraps and the only pieces I have big enough for handles are brittle hardwoods with flaws. I may just end up buying handles from the hardware store for now. If they last it'll be worth the money. Thomas, I'll be sure to look at the grain, thanks for the tip. To clarify, I'm looking for ones where the grain doesn't end on the side of the handle, right? I want it to go through from end to end, right? I would love to work with local wood but I live in an urban area. There's some wood I think I can legally salvage but not many opportunities overall.


As far as construction, I think I'll take to heart what you're saying about glue and finishes, Glenn. I was hoping to avoid doing a true thorough oil finish (I have no patience haha), but I'm more sick of having to replace hammer handles now. That being said, there's no chance of a water based lacquer or shellac version of this treatment, is there? Also, what does submerging the hammer accomplish? Is it to let the oil mix seep into the joint in the eye? I'll hold off on the metal wedges until I need them, as many have suggested. To clarify, when you say make a slot with a little kerf, you mean to file in a little flare to the slot, right?

As far as technique, I don't think I've ever abused this 16oz because I save it for gentle persuasion tasks, but I'll be extra careful.

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Yes the grain should run from one end to the other.  This is why split blanks are better than sawn blanks as the splitting follows the grain.

Urban area---YOU ARE SO LUCKY!  Urban areas have a much greater range of woods than rural ones do as folks plant trees of varieties not found locally.  You may need to contact a tree service to see if they can hook you up with some hardwoods to try.  Got any BBQ places that use hickory logs?  You might be able to buy one off them.

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I found a bunch, well 4, of sledge hammer handles at the local hardware store for $3 each last summer. They had them in the gardening section mixed in with shovel and the like handles. I can honestly say that i have never broken a hickory handle when using the tool properly. Notice i said properly, i have broken many becuase of my temper. I tend to have a short fuse and when i get mad something has to get broken before i am happy again. 

About those wedges, have you tried one of the round steel wedges? I have only treid a couple so i can not say if they are better or not myself but i have heard many folks swear by them. 

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I've had excellent results using clear straight grained hickory from a cabinet lumber store, I bought a 5/4" x 6" x 6' board and it's lasted years for handles. 

I'm wondering about your transition point where the handle leaves the head. I leave the handle a LITTLE larger than the handle eye so there's a bit of a shoulder. 

Soaking the wood with BLO causes it to expand in the eye and stay tight. 

I like the wood glue lube for the wooden wedge, thank you Glenn. Use a saw to cut a slot for the wedge but don't cut it the full length of the handle eye, you only need it to get the wedge started, I cut them about 1/2 the thickness of the hammer head and always in line with the hammer head, NEVER across it. Line the saw blade from face to pein of the hammer head, it leaves the split wood with it's strongest direction in line with the forces applied in a hammer blow. Make sense? 

All in all though, good wood is a must. An excellent source of B Ball bats is the trash can outside the boy's gym at the local high school during season of course. I collected a lifetime supply of broken hockey sticks that way. I use hockey sticks for top tool handles, I don't swing them so small is fine and hockey sticks are plenty tough enough.

Frosty The Lucky.

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Thomas, I hadn't thought of it that way before. I'll definitely get in touch with the tree services folks. Thanks! What do you do as far as drying? Last thing I want is to feel a creepy crawly on my hammer hand :D I asked around and all the city's ash trees got taken out recently because the emerald ash borer came to town. If the city wasn't in shambles because of covid I would head to the municipal landfills and see what I could scrounge. Definitely something I'll keep an eye out for in the future.

BillyBones, I keep hearing people highly recommend these round steel wedges but I can't find them at any of the local stores. I'm ordering a batch off the ebays for future use.

Frosty, I've been leaving the transition pretty square, with about 1/16th to 1/8th-ish of a flat surface under the eye. Too much? Also, if the oil is to expand the wood, then that rules out any hope of a water-based, shellac, or lacquer process. Shucks. I'll probably end up buying a hickory board like you did unless I get lucky and find reclaimed materials.

I got myself a hardware store handle, fit it up better on the sander, and used that today. The handle was pre-slotted, and they did a very sloppy job. I probably should have cut off the pre-shaped insert but too late now I put the wooden wedge in with glue. It's sitting in the linseed and mineral spirits now. Thanks all!

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Purchasing new hammer handles from a supplier are not that expensive.  They come already profiled as a hammer handle with good grain orientation.

When you consider your time making a hammer handle from scratch , , ,

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I know hammer handles in my local hardware store are between $8 and $12, so Glenn is dead on when you weigh that cost with the time to make one.

My loocal store does not carry those round wedges either. The only ones i have used have been recycled, from hammers i slammed on the ground and broke...

My top tools, all 3, and my wooden mallet all have honeysuckle handles. That is the convenience of having a huge honeysuckle next to the shop though. As a side note for the mallet i should have chosen something other than white oak, stinks when it burns. 

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Don’t get to hung up on the water based finish on hammer handles. I’ve been using BLO and it has worked out fantastic. It’s a self hardening penetrating oil. Actually hardens the surface of the wood, and there are no VOCs to worry about. I’ve come to learn the BLO is very versatile around the shop. (Just don’t let a BLO soaked rag or paper towel around. It heat up as it polymerizes and can spontaneously combust. Just ask King Tut.)

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All the warnings we got from elementary school on about "oily rags" being dangerous and subject to spontaneous combustion refer to linseed oil, not petroleum oil.  The use of linseed oil has decreased over the years but the warning has persisted.  Even firefighters and fire prevention folk often do not know the difference.  That said, it is when your linseed oil soaked rags are confined and cannot disperse the heat that is dangerous.  I always just lay them out flat or hung over something to dry overnight.  At most, if you touch them during the drying process thy will be slightly warm.

"By hammer and hand all arts do stand." 

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I'm familiar with the combustion risks for linseed oil soaked rags. Made that mistake once with lacquer thinner when I worked for a GC right out of high school. I was mostly bummed about oil finishing just because it takes forever and a half, no other reason. I did not know that about King Tut! That's pretty cool.

Glenn and BillyBones, I'm really starting to appreciate the value in the time and hassle savings. Thank you both.

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Drying: cut in winter if possible when the sap is down, cut long and split out billets. Treat the ends so they don't dry faster.  Then I like to screw in cup hooks so I can hang them on a wire with air on all sides.  Out of the way as you need to forget them for a couple of years; though my osage orange was prepped in Arkansas and we've spent 15 years in Ohio and 16 in New Mexico  since then...

Hmmm maybe I should plant some osage orange trees on my land back in AR...

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Guess what I broke this time! Another handle I made last year from the same concrete tamper! Who'da thunk! Cracked start all the way inside the eye, followed the grain, and split the handle. I may not be doing too well in the forging department but I'm getting really good at making wooden shivs :D

IMG_20201121_161249.jpg.2b3c47742e5cdcbc306eef26ce56591d.jpg

Going to start seriously looking for material after Thanksgiving.

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Seems like that is too many broken handles.  Time to compare all three for common problems, flaws, etc.

It may be your swing.  Hold the hammer handle loosely and do not push it toward the impact.  Let the hammer head do the work.

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On the bottom side of the pic of the handle, up near the head is a small divot in the wood. You did not have a missed blow at one point and hit with the handle and not the head did you?  I know seems kind of no brainer not to do it, but when diagnosing a problem start with the basics. 

This may help some. Make a list of things that will cuase the handle to break. Things like missed blow, loose head, etc. Then go one by one and eliminate each until you discover the cuase. Oh and do not assume, make sure. Make sure that the head was not working loose, do not assume that since you have been using the hammer for the past year it was still tight (as an example, i know kind of hard after it is broken.)

 

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Forget the tamper handle! It's only good for longitudinal forces and not strong ones at that, you don't ram tampers into the ground, you lift them a few inches, foot at most and let them fall with a LITTLE extra. Trying to slam them down only tires you out faster without significant improvement to compaction, a broom handle works just fine on a tamper. 

A hammer needs to resist bending moments and impact shock, any flaws are stress risers and failure initiation points. If the shoulders at the head are sharp you might want to soften the inside corner for the same reason you don't forge a sharp inside corner. It's not as much an issue with wood but it CAN contribute to issues.

Frosty The Lucky.

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Glenn, I think you're right that I am rough on my hammers due to poor technique. I am actively working to improve my form. I can almost control a 2lb hammer these days without gripping it. But this hammer head was loose from the moment I put that handle on, so I think this was a case of poor assembly on my part rather than abuse. I will still follow your suggestion!

BillyBones, it's possible but the last few weeks my swing been not bad accuracy-wise. I did let a friend use the hammer though, and he was all over the place. Snapped my punch rack off the anvil stand with a miss :D. Best I could do was keep him from putting hot steel down on my landlord's jointer. But one thing you said that I forgot to mention was that this hammer was loosey-goosey from the time I assembled it. It would creep up the eye insert by about 3/16" or so. I never fixed it because I got frustrated and wanted to move on. Whoops. Probably not a coincidence that the split started inside the eye.

Frosty, I hear you loud and clear. With this handle broken, only one of my hammers still has a handle made out of that tamper, a 2.5lb hot-cut cross peen that doesn't see a whole lot of use. Once I get my hands on materials I'll pre-emptively replace that one too. Thanks for the info on sharp corners. I'll take the time to hit the inside corners with needle files going forward.

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Failure Analysis:

Show us photos of what your hitting, the hammer used, how the hammer contacts the work, etc.  Show us the way you are gripping the hammer handle, from both sides.  Once we actually see what you are doing, we can then make specific suggestions.

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Just kidding, got time to a squeeze in a reaaal quick post.

Most of what I did recently was kitchen knives. Included an unfinished blank with the next photo showing my basic grip (no tongs because one hand for the camera!).

IMG_20201122_163627.thumb.jpg.8b80280379a761c63a25d368ff16bf9f.jpg

Side views of my grip:

IMG_20201122_163646.jpg.b92318d580c1c726a5204c4d82aa6470.jpg

IMG_20201122_163653.jpg.12c2a415f7fd3a21ee542ef2118e86d9.jpg

IMG_20201122_163701.jpg.99ef7216fdfb0d100f5eb3d966697d38.jpg

 

I change grips when raising (not swinging down, that has the same grip as above) a hammer that's more than 2lbs:

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IMG_20201122_163709.jpg.5e5374cda2ed81898040edd5200e11bc.jpg

 

Sorry I know that's a lot of uncropped photos. I resized them as quickly as I could. Going on a trip.

 

The hammer used wasn't this hammer in the grip photos. The hammer I use 80% of the time is the rounding hammer I snapped. Same grip, but I don't change grips when lifting the rounding hammer.

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