Replies

1. 
   | Apr 13, 2006 03:53pm | #1

   Hello Ron,

    

   That's a good question. I am no expert but, I have had some success with my hand plans and can offer this. I do not think that there is a hard fast rule as to the correct gap for the mouth setting, rather, It is a matter of adjusting it to get the best results with the material, and thickness of the cut you want to take from that material. Only careful adjustments and test cuts on the material in question will determine the proper settings. For example, a fine cut on straight grained (quartered) pine will require a different setting than that of curly hard maple. Do'nt get to hung-up on "the right setting", there is no one size fits all formula, just good old experience gained from using your tools, and setting them for the best performance for the material and task at hand.

   Bob, Tupper Lake, NY

1. 
   Ronaway | Apr 13, 2006 05:20pm | #2

   Bob, thanks for your reply. I have used the strategies that you mention while using planes with adjustable frogs. I quess I should have been more specific in my initial post as I was really referring to setting the throat on newly constructed infill type planes where you really only get one shot. Once it's too big it's too big.Ron

2. 
   RMillard | Apr 14, 2006 01:53am | #3

   The size of the throat, in my experience is one of the least important aspects of how well a plane works. I never change the throat on my planes, and I honestly don't know what they are set at, as far as dimensions are concerned.  In the case of standard Bailey type planes, I set the frog so that, it and the rear edge of the opening are in the same line. This provides maximum support to the iron. In other words, placing the frog too far forward in order to get the tightest possible throat, would leave the last bit of the iron unsupported. Now this may not be a big deal, but could cause chatter.

   The characteristic that has the most impact on the quality of the surface ( other than the obvious one of sharpness) is the bed angle. I have no experience with low angle planes, but geometry tells me they wouldn't be as effective as a plane with a high bed angle. I'm able to plane with ease, difficult grain using the LN 4 1/2 fitted with the high angle frog. The same goes for the 2 wooden planes I made with  a      52 1/2° bed angle, one of which has a very wide throat.

   Rob Millard

   http://www.americanfederalperiod.com

    

1. 
   Malcolm | Apr 14, 2006 06:35am | #4

   I'm with you Rob!

   A super fine (or even just fine) mouth is great in non-resinous bone-dry hardwood, with the blade set to take whisper-thin shavings.

   Set a bit coarser, run into a bit of resin, or any other stickyness, or even just a crinkly shaving, and the mouth clogs instantly. Just one shaving not clearing can cause a blockage. A half mm wider and the problem disappears.

   I wonder if our reviewer in WA has tested this? Derek?

   Malcolmhttp://www.macpherson.co.nz

1. 
   derekcohen | Apr 14, 2006 09:20am | #5

   Hi Malcolm

   This is a really interesting issue, one about which I have some observations and opinions, but hardly consider to be definitive answers.

   On the resinous and hard, short-grained Australian woods I use, high cutting angles are the norm. It is recommended that planes, such as the HNT Gordon Smoother (which is sitting in front of me), have a bed of 60 degrees. The mouth on mine (as it is set - not fiddling around) is 0.35mm or 1/64" wide. This does not jamb up 90% of the time. In contrast, I have an infill I made several years ago with a totally rediculous mouth - 0.1mm (!) - and I can only use this as a very fine finish smoother on this type of wood since, although it takes amazingly fine shavings, it will jamb up quickly. I would open the mouth on it but it serves a purpose. On longer grained, drier wood it continues to work well.

   The point here is that short grained timber which is as you say more resinous, has a tendency to become crinkly, and this does not clear easily from very tight mouths.

   Now the issue is really whether a tight mouth is even needed. The fact is that cutting angles about 60 degrees really do not benefit from a tight mouth at all since they are getting closer to a scraping action than a slicing action (e.g. think of the wide mouth of a #112 scraping plane). I do see a tight mouth being helpful, but this is only when the cutting angle is low/lowish (say 45 degrees and under) and you are planing timber that want to lift, such as areas with reversing grain.

   I asked Karl Holtey about this and he said to me "I believe in common angle - this is one of the most critical factor regarding tear out and don't believe in tight mouths".

   In my opinion, cutting angle is by far more important than the size of the mouth. At the same time, they are several other factors that influence the performance of a plane (such as the iron-bed interaction, the ability of the iron to absorb shock, and its ability to resist moving once set). So it is simplistic to see one aspect as determining performance outcome.

   At present I am re-stuffing a Spiers infill smoother and the bed is going to be 50 degrees. The mouth will end up about the same as the Gordon. I am trying to give the other areas more attention since the plane is going to be a user.

   Regards from Perth

   Derek

   Edited 4/14/2006 2:41 am ET by derekcohen

1. 
   Malcolm | Apr 14, 2006 10:40am | #6

   I agree, Derek. With the luxury of several smoothers, you'll have one with a very tight mouth for the ultimate smoothing. You'll ease the outside corners of the blade to eliminate edgemarks, keep it really sharp, and get PDC to a cut surface you can polish (whatever that guy in Scotland says).

   But in reality, for 99% of us, compromise is the order of the day. And as you say, there are many more important variables than mouth tightness! I've been making BD smoothers with 50 degree cutting angles, and they seem to work equally well, regardless of the gap. I haven't tested that, though, and I'm not sure how I objectively could!

   Malcolmhttp://www.macpherson.co.nz