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Tuesday, June 26, 2012

Back irons, pt 3

In part two we looked at the back iron for a jack plane. Now lets have a look at the role of the back iron in a smooth plane. I have an old Lakeside #3 size plane that I've never been able to tune all that well, don't know why, but I have just had a hard time with it. Like my jack plane, it has a two inch iron. Anyway, the fit of the cutting iron and back iron looks decent. Let's see how it performs.
The smoother set to go. I have the back iron set at .010" from the cutting edge.

Here's the shavings at that setting. They aren't the best.
The plane was hard to push. Why? Well it would seem that the chips were clogging on the back iron.
I pulled the back iron off and found that chips had found their way between the cutting iron and back iron. This isn't good at all.
I moved the back iron to a setting of .020" from the cutting edge. The plane was much easier to push, the shavings were better, and NO clogging.
There's another problem with setting up this plane. I've come to the conclusion that the back iron is not original to the plane. To set the cutting depth the adjusting wheel is almost all the way back. Remember that the wheel goes back to adjust the blade forward. However, as long as it can be set, I'm happy...though it is a bit wonky. What is all of this leading to? Where is this guy going with all this back iron business? Does he even know?
Sort of. As with most things in my life I'm kinda sorta wingin' it. Anyway, I had bought a 2" back iron from Lee Valley. I wanted to fiddle around a bit and have a base line to compare the performance of the LV back iron to. Let's see how it performed.
Here's a 2" Lee Valley/Veritas back iron. It is very well made...just like everything else from LV (shameless plug, hint they're reading this)
From the side, the LV back iron is dramatically different from a traditional back iron. These are ground to perfection with the back angle already machined into the leading edge. This is a plug and play operation.

Nice tight fit between the back iron and cutting iron. No fuss at all. Remove the old back iron and install this guy, and you're off to the races.
These shavings were made with the back iron set at .010". Not a lot of the scrunching that occurred with the stock back iron. The plane had a pretty decent feel as well.

Here I moved the LV back iron to .020" from the cutting edge. Again, the performance was quite good.
Alright. How do I conclude part 3? Do I tell you to run out and buy a new back iron? Do I tell you to save your money and spend the time prepping the existing one? Well, just like everyone else out there, I have an opinion. If you're still reading, I'll go out on a limb and assume you want to hear it.
If you have a smoother and you want to improve its performance, by all means, buy an LV back iron. It is a nice piece. It's easy to set up and performs well (hey, listening?). Setting up a back iron can be a tricky process, and LV has helped to take a lot of the frustration out of it.
Do you NEED one? No, you don't. You want it though.
For my particular plane there was more than just the ease of setting the irons up. The position of the adjuster slot in the LV back iron is much more friendly to my plane than the back iron I had. My adjustment wheel is closer to the middle than all the way out the end like it had been. I also found that lateral adjustments went a bit easier. How could that be? The lever cap contacts the hump of a traditional back iron. The hump is a radius, as you move the iron assembly to one side or the other to correct the alignment, the contact between the lever cap and back iron changes. The back side of the LV back iron is flat. Dead flat. The contact area between the lever cap and back iron is consistent over the entire range of adjustments.
Now, what about the jack plane that we started with? I'd save my money and buy a spare iron or some other tool. Being a roughing tool, you can get the original back iron into reasonable shape and set it back off of the cutting edge and get great results. Like I said, it's a roughing tool. I wish I had a jointer that I could test this out with.
In addition, if I had a rehab plane with a bad back iron (be it a jack or a smoother) I would replace it with an LV back iron. Set up time is reduced, along with headaches.

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