knives on sickle bar

I have to replace one knife on the bar of a mower-conditioner. I understand that riveting is the standard practice. Is there anything special I need to know about this?

You can replace them on the mower if you have to. Just grind the rivets off against the section and knock it off. Set it on or hold a heavy piece of metal against the rivet heads on the new section, against the bar and smash em down with a hammer.

If I understand the question, you can replace the rivets with bolts with lock nuts. If I don't understand the question then disregard.

I replaced all the sections on a JD 7' sickle bar mower last year and used the bolts and lock nuts they've come out with. If I have to do it again, I'll go back to rivets.

Get a sickle repair tool. Saves a lot of bending the knifeback, whacking rivets with a hammer, and swearing!
ONE example

Since it sounds like you're new to this - if you haven't, pull the cutter bar. Yes, it's possible to replace the sections in place with a rivet tool, but better to get familiar with your machine.

You can use bolts instead of rivets - but, depending on the hold down clamps you have (I forget the technical term for those clamps) the bolts may not fit under them - then you'd have to replace all the clamps. Not worth it.

The rivets are easy enough anyways. For now stick with them.

Pulling the cutter bar will also allow you to inspect all the sections - replace any that are questionable (if not all of them), and fix any that are loose.

To remove a section (blade) I use a vise as a sort of anvil. open the jaws just enough to pub the section straight down into it - but closed enough so the cutter bar itself rests on the top edge of the vise jaw. Smack the section blade down hard with a 4 pound hammer right over each old rivet. They'll pop right off (and shoot around the room - so protect your eyes)

Very simple once you get the hang of it.

Put new ones on - lay the bar on a hard surface, and hammer the rivet down. No heat or anything needed. I use a ball peen hammer and peen the edges over all around, then smack it down tight.

Using the tool is a better option as over-hammering will distort the bar especially over time, and you don't want that. But if you're looking to get cutting right away - don't worry about hammering, just do it, use common sense, and you'll be fine. Just make them tight - you don't have to smash them into submission.

(buy the tool though, this isn't the last time you'll be doing this)

Pay attention to the sections you buy - if using serrated, note that there are usually options of over serrated, and under serrated - get the right ones. (serrations either on top or bottom)

While the cutter bar's out - inspect your rock guards.

Sickles are like scissors, both sides need to be in good shape to cut.

Make sure where the sickle sections cut against the rock guards that the edges are not rounded. Make sure they're all even as well, so that there aren't big gaps between the guard and the section when the bar's installed - just picture cutting with scissors if the blades have a gap.

Hard to describe, but I use a large adjustable wrench with a long pipe to "tweak" the rock guards up or down as needed.

one final suggestion - if your guards are in bad shape - and you're using regular rock guards - now might be a good time to go to stub guards if appropriate to your situation. I like them because I've never gotten a clog since going with them.

Good luck.

We use bolt in's on our 250 side mount, and I like them over rivets,,when you knock out rivet knives and when you replace them with out a tool you can/will reshape the back bar to a nasty direction,,with the bolt in's there is no stress on the back bar..

I also like the rivets just whack em with a big hammer!

I helped Dad remove the blades the same way. About all I did was hold the blade bar. Stan

I think I must have had the best Vo-Ag teacher in the world!! He taught us how to make a rivet setter out of piece of cold roll shaft. All we did was drill a divot in one end. Can't remember the size of the drill bit now. Lay the sickle on the anvil, and hit her hard!!!

Size it to the size of the rivet head. Weld a plate on the other end, to stabilize it. Better yet to buy the tool (and an extra punch point- cuz they do break)...or change over to the bolts. Much nicer setup.

I remember my dad knocking the rivet heads off with a cold chisel, then driving the rivet out with a center punch.

If you torque them properly you won't have a problem

You would not want to use a center puch as they would want to expand the rivit and tighten it up. You would use a flat end pin or small enough alighnement punch to drive them out. That flat end would not try to expand things like a center punch would.

I would never go back to rivets. Was involved with replacing sections on 12 30' platforms and six 40' platforms on the harvest for thirteen years, all with bolt on sections. We replaced thousands of knife sections. Once you learn the feel of tightening the nuts the sections stay tight until they need to be replaced. If we broke a sickle I would remove the bolts and sections from the broken sickle in my spare time for reuse. I have twisted off a few bolts trying to get them "just a little tighter" so it does take a little time to get the feel. Also, there are the bolts that need to be held from turning with an allen wrench. If a person does have this kind of bolt I can see why he would want to go back to rivets! The bolts I am talking about are splined on the sides and are a press fit in the hole.

You are correct.

(quoted from post at 14:07:32 06/19/16) Since it sounds like you're new to this - if you haven't, pull the cutter bar. Yes, it's possible to replace the sections in place with a rivet tool, but better to get familiar with your machine.

You can use bolts instead of rivets - but, depending on the hold down clamps you have (I forget the technical term for those clamps) the bolts may not fit under them - then you'd have to replace all the clamps. Not worth it.

Click to expand...

If your hold downs are the low type, try putting the bolt in from the top instead of from the bottom. I haven't seen many set ups where having the nut on the bottom won't work.