Welding high(er) carbon steel

I have a garden tiller (that I got at the dump). In use it leaves about a 6" wide untilled strip in the middle. I want to reduce this by
extending the middle blades/tines. The easiest, fastest way is to weld pieces on. But the tines are pretty hard, to resist being worn down, and I feel that just welding on them will leave a brittle HAZ.
Will this work: anneal them, weld on the extensions, re-harden, and temper? I hope so, 'cause the alternative is drilling & bolting and I find that very unappealing. And sure to work loose.
Thanks, Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bob Engelhardt wrote:

(...)
Rivets?
http://www.smithtoolinfo.com/r3030.htm http://cgi.ebay.com/rivet-tool-new-old-stock-farm-implement-IH-JD-NH-Ford_W0QQitemZ270476151140QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef9a28964 http://cgi.ebay.com/rivet-anvil-tool-farm-implement-IH-JD-NH-Ford-mower_W0QQitemZ270476152396QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef9a28e4c
Magic Sickle Hardware?
http://www.tractorsupply.com/agriculture-farming-ranching/mowing-haying-harvesting/other-mowing-haying-parts/5-8-in-section-bolt-with-nut-for-10-ft-sickles-1204005
--Winston
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bob Engelhardt wrote:

Or, can I just weld without annealing, then temper to relieve the HAZ?
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The steel is likely some .7% to .9% carbon steel. That is going to be high enough to give you nasty weld issues. But it also begs the question of what stock are you planning on welding on? Some plain hot rolled bar stock is not going to cut it.
Option 1 is to weld then completely heat treat. That will leave you with a lower carbon section in the weld area, it will bend. Option 2 is to preheat, weld, cool slowly. That will soften the tines, the whole thing will bend. Option 3 is to weld, cool the joint as slowly as possible. That will keep the HAZ to something moderate, still likely to bend. I think I would just weld it up let the joint get hard, use the torch to temper the joint to around 800 degrees, see if hold up.
Bob Engelhardt wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RoyJ wrote:

I was to use some OCS (Old Chevy Spring). In fact, the original plan was to use the OCS to make whole new tines, but there were complications.

Thanks. Not what I *wanted* to hear, but what I needed to hear. The bottom line seems to be that no matter how I do it, it's likely to be soft somewhere. Then I'd be stuck & worse off.
Maybe drilling & bolting isn't that bad of an idea. Maybe pinning & bolting.
Oh, wait - here's an idea: if I do the welding along the edges of the tines & not across them, then with option 1 or 3 (softness in the HAZ only) I wouldn't get bending. The leading edge would wear faster, but I can handle that. Or use plug welds & avoid the soft edges too.
Thanks again, Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

about

Just a stupid question here, Bob, but did the tiller come with its drag stake?
This is a metal bar that is fitted between the sets of rotating tines to both reduce the pullback force and to act as a "middlebuster" as it is pulled through that untilled strip in the middle.
If it didn't have one, it *should* still have the bracket to which it would be attached.
A suitable piece of bar stock (.250/.375 x 1.0) can be easily drilled to make a replacement stake.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RAM wrote:

I think we have a winner! You're right - there is a "leg" in the middle, with drilled holes, but something is missing. I didn't really accept that the tiller was supposed to leave such a wide strip ... but there it was.
Now, this "drag stake": would is it supposed to look like, geometry wise?
Thanks! Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
says...

I've seen them made similar to a miniature plow head (like a horizontal arrowhead with a vertical bar attached at the midline) or built like a simple "T" shape, with the flanges going to the sides, not front to back.
It provides a certain amount of drag as it cuts dirt to compensate for the speed of the tines, otherwise the machine would run away from you, or on a tractor, it would be pushing you.
Some are adjustable (picture an adjustible hitch setup, where you pull the pin to slide the bar up/down to set depth), some are fixed.
Geometry is usually designed to either simply provide a leg for the machine to stand on- avoiding damage to the tines. Or it is designed to actually dig in (arrowhead shape) and can be adusted for depth control. Either design should slow down forward velocity and encourage digging by the tines. Just don't angle the arrowhead too steep-- I would recommend keeping it within 5 degrees of flat.
Good Luck!
--
Tin Lizzie
"Elephant: A mouse built to government specifications."-Lazarus Long
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
TinLizziedl wrote:

I just took another look at my bar. It is L-shaped with the long vertical leg drilled every inch or so for height adjustment (held by a pin). The short horizontal leg has 2 holes that must have held the breaker bar. E.g., a plow or arrow.
I had assumed that this was just a leg to keep the tines at a certain depth. Although it didn't work real well for that.
Something I didn't mention is that the tiller is rear tined & self propelled (driven wheels). So that it doesn't need to be held back - it goes at the wheel speed.
Thanks, Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On mine the drag bar is angled at about 15 degrees off vertical, facing forward. It is completely free to pivot forward, locked so it cannot go past the operating position. In use you jam it into the ground to counteract the tines, lift up slightly on the handlebars to let it claw forward, then push down on the handlebars. When you come to the end of a row you shut off the tines, pull back, the drag bar pivots out of the way. For transport, the drag bar has an extra hole that lets you position it out of the way, just drive it on the tongs.
My unit is buried (deeply ) in the shed, IIRC it is 3/8" x 2" plain bar stock (not hardened) with a 45 degree cut on the business end, holes abut every 2" for depth adjustment,and the aforementioned transport hole.
Bob Engelhardt wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RoyJ wrote:

Thanks, I think that I have the picture now. Mine isn't angled (much, at any rate) & doesn't pivot, for sure. And has a trailing leg that held some kind of cutter, I think.
I'm going to make up a cutter to bolt on & try it. WAY easier than the tine extensions that I was planning!!
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
What's that Lassie? You say that Bob Engelhardt fell down the old sci.engr.joining.welding mine and will die if we don't mount a rescue by Fri, 30 Oct 2009 20:16:50 -0400:

If you ever do need to weld something to high carbon steel, my old welding text book says:
Pre-heat to 700-900 F., use a nickel rod for ductility, cool slow.
--

Dan H.
northshore MA.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
replying to Bob Engelhardt, mariaarcia wrote: The unfinished surface of high carbon steels is dark gray and similar to other steels.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.