Friday, January 28, 2011

Making Basic Shapes with a #6 Hollow and #6 Round

Chris Schwarz addressed the oft asked question "how do I get started in hand tool woodworking?" today on his blog. My transition to hand tools started with dovetails. My move to planes happened in a cry for 'mercy'. I had a six inch jointer and wanted an 8. I read how everybody that had an 8 wanted a 12 and everybody that had a 12 wished they had, at times, an 18. If the person answering had a 24" planer you don't want to know for what they yearned. I bought a couple stanleys and a ridiculous pink workbench instead of chasing that high and have never wished for a wider jointer since.

For many hobbyists hand planes are a strangely logical solution. My decision was not a fulfillment of a secret desire to live centuries ago. Using hand planes for flattening a single side before running it through my planer was based only in practicality. I imagine hand planes are practical in most shops, but to varying degrees.

My transition to molding planes occurred in a similar cry for 'mercy.' I was looking through Amana's web page trying to find something specific and ended up dropping $85 on a compromise.


I never get asked Chris' question. I often feel like I am the last step. Like a try and a fore plane, however, hollows and rounds are relevant and a strangely logical solution to many hobbyists journey and craft. The solution they offer--flexibility--is practical; the means by which they offer it--putting your hand to your work--is wonderful.

A few weeks ago I posted a couple entries detailing several things that can be done with only a #6 hollow or a #6 round. Let us take a quick look at what can be done with a single pair in combination.





Ogee (60 degree circle segments at 30 degrees) with Fillet
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Ogee (60 degree circle segments at 60 degrees) with Fillet
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Ogee (90 degree circle segments) with fillet
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(disregard the quirk)



Reverse Ogee
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Ovolo and Cove 
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90 degree Cove and Ovolo
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(60 degree ovularish) Cove and (90 degree) Ovolo
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Or would you like the oval the other way?
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etc., etc., ETC!...

That's 27 different profiles illustrated that can be created with one hollow and/or one round.

We've looked at making rabbets
We've looked at steering planes with rabbets
We've looked at using rabbets as depth gauges.
We've looked at laying these shapes out before.

Stay tuned. We'll take a look at what can be done with two pairs. You'll see why I always recommend starting with more pairs than one: we can probably come up with 100 profiles with just 2 pairs. 

We'll also execute the supporting molding and top edge of the John Townsend chest in the Metropolitan Museum of Arts with no new tooling, no real compromises and a few work-arounds.

Clearly, it's pretty difficult to keep up with a router.

Skewed Rabbet vs. Straight Rabbet

I often get questions regarding skewed irons vs. straight iron. My original set of hollows and rounds have a slight skew to them. The skew is slight and might be 5 degrees. When I started making my own planes I made them with straight irons and have not looked back. I do little across the grain and the few times I do I usually just deal with the deficiencies, which my experience tells me is primarily a mouth that clogs and secondarily a less than perfect surface. 

I am about to send out a skewed rabbet and thought you might like to see the difference. It's obvious.

Skewed Rabbet.
video
Notice that everything is coming out cleanly. The shavings are held together as they are ejected by the structure of the wood. The skewed iron is in contact with a single point of several fibers at any given instant during the cut. (Please forgive the awkward way I'm holding the plane, I wanted to let you see.)

Now on to the straight iron. (Note: I intended to show you a more productive example, but this was just too perfect. Look inside the mouth.)
video
The shaving has no strength to it since there is no shearing action. At any given time during the cut the iron's edge is in contact with a single fiber across the iron's width and fiber's length. Due to this, the shaving always falls apart and it often happens in the mouth. 

So the next question is 'Should I get a skewed rabbet instead of a straight rabbet?' It depends on how you work. Do you do a lot across the grain? I personally won't give up my straight rabbet. Again, I find it much easier to be aggressive with a straight iron and I have much more control...with the grain. 

Is your experience different?

Friday, January 21, 2011

Correcting Mistakes with Hollows and Rounds

When I have illustrated the steps for cutting various profiles I have quoted the dimensions in 64ths. I have been asked on several occasions if it's necessary to be that accurate. The answer is "no." My approach is nowhere near as mathematical. I typically lay the profile out on a piece of paper, transfer the profile to the wood and draw my rabbets there. I get it pretty close. I quote in 64ths simply because those are the measurements with which I initiated attack.

Layout, transferring layout, and execution of the rabbets laid out is most of the skill. Work with the profiled planes is dictated by this layout.


Transferred Layout. You can see that the line of the ogee is not parallel to the tips of the rabbets that guide the round. I made my rabbet slightly wider and not as deep. You can see below that I removed the vertical pencil line and left the horizontal.

Note that the tips of the rabbets for the lower portion to be profiled with the round are now parallel to the profile of the ogee. (Roughed out on a table saw, touched up with a rabbet plane.)

Mistakes happen. Recognizing mistakes and correcting them early is crucial. Check your progress.

We have discussed how hollows and rounds are difficult to steer and that steering should be done with the rabbet plane. But what do you do when a chamfer is wrong?



Note that I am intentionally laying out the chamfer for the hollow to follow out of line with the profile of the ogee.


The chamfer is cut at an angle that is too shallow


The profile left by the hollow is out of line with intentions.


I took my rabbet out and reestablished a chamfer that is much steeper and more accurate.


Goal achieved.


Complete

If your rabbets for the lower portion are out of line, a similar correction can be made. It's important to check you progress and recognize errors early. If you don't adjust for mistakes early you will end up pressing the the plane against the profile while trying to cut with only a portion of the iron--a difficult and inaccurate process.

As your accuracy increases your scraping at the end decreases.