Tire Hammer Dies

[anvilstrkr]

Has anyone out there had a problem with weld cracking where the die attaches to 1/2" plate that bolts to hammer?

 

I was told this is a accident waiting to happen. Because of the heat treat process.

[forgemaster]

When I read this my 1st thought was, so sad, I hope it was quick.  then I realised it was about dies for a power hammer.

 

Phil

[IronAlchemy]

Anvilstrkr,

 

I have built a few dozen tirehammer dies. We did have a few failures among the first few dies we welded. It was not a disaster any worse that the bolts for the dies coming loose which happens to me every time I use the hammer. Actually, I have never seen a hammer of any make that did not have the dies loosen from time to time. Re-welding properly seems to have fixed any problems.

 

I attribute the failures to too low a temperature in the preheat for the weld. You really need to keep the temperature of the assembly between 400 and 600 F. I know of no metallurgical reason that the heat treatment would cause a problem. We have been using S7 for dies. 4140 is quite a bit more forgiving.

 

Did the individual who expressed concerns to you give you any specific reasons why they felt the heat treatment would cause problems with the weld?

 

Regs,

Doug Wilson

[plain ol Bill]

Get them hot - weld with 7018 - let cool slowly - use them.

[Bruno C.]

Get them hot - weld with 7018 - let cool slowly - use them.

 

Great Advice.   Preheating large chunks of metal can be expensive, and one of those little home depot torch's won't cut it.

I like my old AC arc welder.  when unsure about a weld I just add more weld, and keep adding, till hitting it real hard won't break it.

The work tends to get real hot, and it's gotta cool down.

 

I do NOT claim to know anything, or do things the right or any logical way.

[MOblacksmith0530]

I had one set of 4140 dies break at the weld when I examined the failure there was poor penetration to the 1/2 inch plate, this was the cause not the heat treat. I gouged out the old bad welds and re-welded ane re-heat treated the dies and they were fine. Other sets that I made and welded myself with preheat prior to welding never failed. We made 30 hammers when mine was made and I only heard of one other set that failed. Not a disaster just a repair.

[FieryFurnace]

I had one of mine break quite some time ago being mild steel plate welded to s7 dies! It was not a dangerous event, even though it came off while running the hammer at full RPM. I rewelded after grinding a substantial weld groove, with plain mig wire. No preheat and no tempering afterwards. The die still holds up to texturing large square stock cold on the diamond, and it is holding up fine. I fixed it about a year ago.

[anvilstrkr]

Thanks for the feedback. To answer Doug about the concern of the weld. He thinks that when I heat treat the die it will absorb the carbon into the welded area. I personally didn't agree with him and I told him I would ask this forum. By the way the die is made of 4140. His suggestion to me was to make the whole die out of one piece and eliminate the weld.<br />I know these hammers have been around for a while and I really haven't heard of any problems.

[kevan]

Great Advice.   Preheating large chunks of metal can be expensive, and one of those little home depot torch's won't cut it.

I like my old AC arc welder.  when unsure about a weld I just add more weld, and keep adding, till hitting it real hard won't break it.

The work tends to get real hot, and it's gotta cool down.

 

I do NOT claim to know anything, or do things the right or any logical way.

Great solid advice......no substitute for more weld....and if it breaks, there was insuffient weld.Deep vee-ing and good penertration normally does the trick. (I too, claim to know nothing)

[Frosty]

Did you scarf the dies before welding? Scarf as it applies to arc welding means grinding the joins to ease penetration without over amping. Preheat, weld and cool slowly, say air cool on a fire brick to normalize, you can anneal of course, both work. Once cool, clean and paint with a good quality enamel paint like Rustoleum or Krylon. The paint is a good advanced indicator of a failing weld. It will begin to peal if a weld is failing as paint doesn't flex with the weld halves.

 

When the paint begins to flake over a weld, peal it up with a scribe and examine the weld. drill a couple stopper holes at each end of a crack, grind (scarf) and reweld.

 

this is simple maintenance in an impact stress zone. NOT something to freak out about, just watch and maintain. No big thing atall atall.

 

Frosty the Lucky.

[Bruno C.]

Did you scarf the dies before welding?

 

Also a good thing to do.

 

As Kevan and Frosty mention, I find this method to work well.   Usually do a rough 45 degree angle on both sides on the bigger welds.

Welding rod's and grinding disk are a whole lot cheaper than a visit to the E.R.          I like to use 6011 for most work since I can weld without much grinding, but I believe

7018 is better if you do a proper surface prep, grinding clean and scarfing the contact points, and a pre/post heat.

 

 

 Once cool, clean and paint with a good quality enamel paint like Rustoleum or Krylon. The paint is a good advanced indicator of a failing weld. It will begin to peal if a weld is failing as paint doesn't flex with the weld halves.

 

When the paint begins to flake over a weld, peal it up with a scribe and examine the weld. drill a couple stopper holes at each end of a crack, grind (scarf) and reweld.

 

Also, good advice.  Lol, That tempt's me to take the wire bruch to the giant rust pile a got stuck together :)

[onetreeforge]

I found when I welded the dies to the plate the plate warped a little bit I think this would make them not sit flat and maby help it crack, I set it up in the lathe and turnd the plate down till it was flat.

[macbruce]

I found when I welded the dies to the plate the plate warped a little bit I think this would make them not sit flat and maby help it crack, I set it up in the lathe and turnd the plate down till it was flat.

I always put a slight curve/crown on the mounting plate before I weld em together in order to counteract the pull that always occures when you weld the two together. It's better to have a slightly concave bottom fit up than convex which makes tightening the bolts evenly a pain in butt.

Welding mild to tool steel with 6011 or common mig wire will stick em together but it will most likely fail in the long run...... :(

You can usually jury rig a 1 lb SS wire spool to work in any mig machine and will do a good job welding tool to mild but you'll need 75/25 (argon and co2) gas to do it.

[onetreeforge]

I always put a slight curve/crown on the mounting plate before I weld em together in order to counteract the pull that always occures when you weld the two together. It's better to have a slightly concave bottom fit up than convex which makes tightening the bolts evenly a pain in butt.

Welding mild to tool steel with 6011 or common mig wire will stick em together but it will most likely fail in the long run...... :(

You can usually jury rig a 1 lb SS wire spool to work in any mig machine and will do a good job welding tool to mild but you'll need 75/25 (argon and co2) gas to do it.

 

I used the mig to weld my 4140 dies to the mild steel with that genral purpus argon cor mix, seems to be holding out so far, if they brake a frind is going to weld them with his atomic hydrogen welder.

 

I have some Massey hammer blocks I want to cut up to make some nice H13 dies but they are brand new and seems a waste

[Backwoods Blacksmith]

Using 4140 or 5160 for dies to be welded to a base need to be preheated to 400 or 500 F before welding and cooled slowly before heat treat.  If not, the weld will break away from the die.  I always tack the dies into position, heat in the forge before welding.  A good 1/4 inch weld detail will allow the die to be welded with plenty of penatration.  Use a temp stick to check the temp.  If you go to 500F by the time you get it out of the forge, into the vice or clamped to the table you will still have plenty of preheat.  Wrap in kayowool or put in annealing bucket overnight.

[ironwolfforgeca]

one thing not suggested here is a better rod then 7018 witch is a good rod to use BUT ! :P  for things that get abused

I use 100-18 next step up- stronger rod I use this rod alot on heavy eqt repair in areas that 7018 will fail sooner or later

pre heat - post heat -cover & walk away Done

 

Steve's welding & fab

[Stormcrow]

I build my power hammer dies out of 4140, heat treated them, ground 45 degree scarfs on the bottom, pre-heated the dies for an hour at 400 degrees in my tempering toaster oven, welded, then post-heated at 400 for an hour again.  No issues, and I'm not much of a welder.

 

I did have to flatten the baseplates back out, but a couple of blocks and my hydraulic press make that easier.  I'm not bolting the dies down, though, since I'm using a different setup that didn't require them to be as precise.

[IronAlchemy]

I have a couple of comments on the comments so far in a good discussion on welding tool steels and dies.

 

I don't think that you will see much difference in ultimate strength between a MIG weld with ER70 wire and 7018 rod. The 7018, in my hands, is easier to get set up and get good penetration but if you set up the MIG for spray transfer, you should see pretty similar results.

 

I think that there are reasons to bevel the edges of the tirehammer dies for the weld. However, remember that this is designed as a fillet weld. with proper settings and good technique you should have plenty of weld area to hold. The failures I have seen and that I hear about are from improper technique and settings for the weld and the weld failing at the boundary, not from the filler metal cracking.  You can surely compensate with more weld area as many have correctly pointed out.

 

One reason to bevel is to keep the same weld area without the fillet interfering with the bolt holes for the die. Depending on the alignment of your anvil and hammer head, the bolts may need to be very close to the die. Sometimes you have to grind off a seat for the bolt if it overlaps the weld. You can achieve the same results by not doing a weld all around and having no weld in the bolt area of the die. I see plenty of dies that have held up well with this approach.

 

When doing our build of tirehammers, I went back and forth quite a bit with Clay about the welding and cupping of the baseplate of the die. His opinion was that a slight cupping of the dies was beneficial in that it provided some spring that kept tension on the bolts and reduced the tendency of the bolts to come loose. I am not sure that I see that in practice and would tend to support the comments of others that flat is good. I'll be doing some testing of the difference over the coming months.

 

Macbruce has a good point about using SS for the weld. That is indeed one of the recommended approaches to welding tool steel to mild steel. I think that there are two main reasons for this recommendation. The SS tends to be more ductile than a high carbon filler. It also has a better color match to tool steels like S7 and H13 so, if cosmetics matter, it makes a real difference. It is definitely not a stronger filler but, I think, is more forgiving. I'll be giving this a try and comparing to my ER70 welded dies.

 

Good discussion. Thanks.

Doug Wilson

[IronAlchemy]

I just wanted to follow up on my last post about the effect of having the back of tire hammer dies flat. I took two sets of dies for my tire hammer, flat and 3" radius, and flattened the backs on a large belt sander. I also filed the tire hammer anvil and hammer to be sure that they were perfectly flat.

 

I have switched out the dies probably half a dozen times over the last month and put at least 20 hours of hard forging on each pair. With the flat backs, neither set of dies came loose at any time as compared to hourly checks of loose dies before. I'd say that is evidence enough for me that tire hammer dies should have flat backs. I'll be flattening the rest of my die collection today and building all future dies with flattened backs.

 

Doug Wilson