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Hand Tools doings #17: Yet more questions about hand cut dovetails and fret saws

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Blog entry by Betsy posted 04-17-2008 03:56 AM 2281 reads 2 times favorited 12 comments Add to Favorites Watch
« Part 16: Sharpening with questions, of course Part 17 of Hand Tools doings series Part 18: Sharpening »

I’ve been using a coping saw to cut out the waste—- but found that it was difficult to use. So I got a fret saw and installed a spiral blade that should work well.

This is the saw I bought.
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Now would someone explain how the tensioning is supposed to work. I’ve installed my blade and its quite taught in the frame. You can pluck it and it “sings” the same note as I would be happy with on the scroll saw. But when I cut with it the blade flexes at least 1/2”. I’m pretty sure that’s not right. So how do you adjust the tension? I’ve tried pushing the frame tighter—- to no avail. I’ve fiddled with the wing nut on top—- same.

Ok – now onto the dovetails issue.

I’ve started doing my final chopping with the board situated so that I can look straight onto the chisel and can tell if the chisel is vertical.

This picture shows the chisel—but the board blends into my workbench.

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Now when you chop down on the board to break away the waste do you move your chisel to the right or the left? Moving to the right seems like it makes a divet in the bottom of the piece—moving to the left seems to break the edge so it’s not crisp.

Seems to me that the divet in the bottom would be the choice—but wanted to put it out there for your opinions.

I am getting better with the dovetails – here is my latest attempt.

My tail board.

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My pin board

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Put together – side view

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top view

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Now – how tight is to tight? I put these together with light taps of my hammer. I’m wondering if this were a real project and I fitted the joint in a dry run – then take it apart to glue that the fact that I compressed the wood the first time it would not fit as well the second time around. But if you don’t test fit before you glue you could end up without a good fit.

Thanks for your help.

-- Like a bad penny, I keep coming back!



12 comments so far

View Woodhacker's profile

Woodhacker

1139 posts in 2474 days


#1 posted 04-17-2008 04:38 AM

Betsy, keep practicing, you’re on the right track. I’m no expert, but I can give you some things to think about from my experiences.

I bought this same fret saw you’re using back in high school…(...a long long time ago). I now use this the same way you’re using it…to cut out dovetail waist. You may have better luck using a non-spiral blade for a couple reasons. The spiral extends to the ends of the blade. As you tighten them you can actually compress the spiral making the clamping less stable, plus it seems to me there’s less surface area (due to the spiral) for the saw to clamp on to… to hold them tightly. As you’re cutting the blade can slide out a little giving it a lot of flex. Another reason I don’t use them is that they’re slightly wider than the kerf on my dovetail saw. You may have better luck with a thin standard blade.

Regarding tension…I think the design of these saws contribute to not being able to get the blade real tight. Even with straight blades you’ll have some flex. I’ve never been able to completely eliminate it. As I approach the end of the cut, I usually slow way down to make sure I don’t go too far on one side or the other.

On you’re chopping with a chisel to clean out the last part of the waste: You’ll find different theories, one says angle the blade slightly into the piece so you create the divot you mention. Others say cut straight down, you can pare out a divot later if you’re inclined to do so. I would definitely not angle your chisel toward the end of the piece. There’s too much risk of denting the joint seam…which will be especially noticeable on the outer side of the piece after assembly. Plus that wouldnt’ really serve any purpose because you’d have a lot of clean up paring to do afterward.

What kind of saw are you using to actually cut the dovetails and pins? That can make a world of difference too. Even though it was quite an investment, I purchased a Lie-Nielsen a few years ago and couldn’t believe how straight and true they track during the cut.

It also looks like you could make your tail and pin cuts a little deeper for the stock you’re using…ideally I like both the pins and tails to extrude about 1/32 inch beyond the joint…that way if you ever dent the very edge of one it will sand off later. Plus it’s a lot eaier to sand the pins tails than sand the entire piece, if the pins/tails aren’t long enough.

Rob Cosman has some excellent videos on hand cut dovetails if you ever get a chance to see them, I recommend them. Well, as I stated early on here…I no expert at all and I’d be interested to see what other say about your dovetail joinery too. I have two projects posted on this site you might take a look at.

http://lumberjocks.com/projects/6954 , and
http://lumberjocks.com/projects/6875

Good luck with your progress.

-- Martin, Kansas

View Woodhacker's profile

Woodhacker

1139 posts in 2474 days


#2 posted 04-17-2008 04:45 AM

Betsy, one other comment, as you strike your chisel to cut out the remaining waste, make sure your “blow” is exactly straight down on the chisel end. Avoid glancing blows at an angle, because that can ruin the preciseness. If the butt end of the chisel moves horizontally at all when you strike it, you can bet the cutting end has moved some slightly too.

-- Martin, Kansas

View GaryK's profile

GaryK

10262 posts in 2739 days


#3 posted 04-17-2008 05:11 AM

You are getting a lot better Betsy. This is your best so far.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View johnjoiner's profile

johnjoiner

160 posts in 2644 days


#4 posted 04-17-2008 05:19 AM

Hi Betsy.

The way I was taught to cut out that waste is to not move the chisel either way. I first push down just with light hand-strength so that I don’t make a dent across the marking line. Then come in from the end of the board and pare out a little sliver. This establishes the smooth edge that will be visible. Now chop down lightly from the top as in your picture, and pare out a larger sliver. Wash rinse, and repeat. The main thing is to just be careful to not bruise the marked line that will be visible in the finished joint. Yours are looking good so you must already be watching that closely.

-- johnjoiner

View Mike Lingenfelter's profile

Mike Lingenfelter

502 posts in 2865 days


#5 posted 04-17-2008 05:47 AM

Betsy,

You are making some real progress with your hand tool skills. I have the same fret saw and with the very thin blades you will never eliminate the flex in the blade. I use a “flat” blade and have good results with it. If you see a lot of flex you need to let up on the pressure. You really don’t need much pressure to make the saw cut. Extra pressure really doesn’t help it cut faster and it can cause you not to cut straight.

With your chisel work, you seem to be cutting past your gauge line. When you are removing that last little bit wood, you need to do it in a few passes. Taking one big chop can cause your chisel to be pushed back across your gauge line. Try taking a few smaller chops and see if that helps.

View Betsy's profile

Betsy

2914 posts in 2647 days


#6 posted 04-17-2008 06:11 AM

Martin thanks for the insight on the fret saw. Mike also suggested using a different blade – so tomorrow I’ll try that. I’ve got the Cosman DVDs on order, hopefully will get them this weekend.

Mike – about the chisel work—- I thought that you were supposed to put your chisel into the gauge line to start your chopping. Are you saying should chop from the middle back and then end with a slicing type cut to clean up the bottom of the socket?

John – are you describing making a knife wall such as you would do to hand cut a dado?

Gary -—- better watch out——pretty soon I’ll be giving you a run for the money when it comes to this woodworking jig!

Oh and Martin – I’ve been using a crown dovetail saw. Not sure I like the single barrell type handle. I’ve ordered the Leinelson open handled saw and hope that will feel better in my hand. (For the price – it had better!)

Thanks again guys. I’m going to master these things yet!

-- Like a bad penny, I keep coming back!

View Mike Lingenfelter's profile

Mike Lingenfelter

502 posts in 2865 days


#7 posted 04-17-2008 04:17 PM

That is correct. If you go right to the gauge without taking more of that waste away, what seems like a small amount of wood can push your chisel back past the gauge line. The more wasted you try to take in one chop increases the compression on the chisel against the wood. It will even cause your chisel to dive in, which isn’t a bad thing, if it’s only a little. The last chop should be a fine one.

Keep up the good work, you are getting better each time you post.

View che's profile

che

123 posts in 2777 days


#8 posted 04-17-2008 04:51 PM

Betsy. I think you’ll like the pistol handle a lot better than the round handle. I predict a huge jump in the accuracy of your cuts with the new saw. Of course if you don’t like it you can sell it on e-bay for what you paid for it. (if not more)

It’s hard to tell from the photos but it looks like you have too much set on your current saw. One or two swipes per side on a coarse stone should help things. Less set will help the saw cut straight on its own and will produce a smoother cut.

Your right about the test fitting Rob Cosman doesn’t test fit the joint. Glue and go.

In photo 2 you want to move the handle of the chisel to the right to clear the waste. Chisel half way, flip and complete the chiseling.

One last tip. Use the largest chisel that you can. it is much easier to keep the line straight with a 3/4” chisel than a 1/4” one.

-- Che.

View johnjoiner's profile

johnjoiner

160 posts in 2644 days


#9 posted 04-17-2008 08:10 PM

Hi Betsy.

“are you describing making a knife wall such as you would do to hand cut a dado?”

Yes, but with your chisel. I think Mike is suggesting a different method where you don’t actually pare (not chop) down on your knife line until you’ve removed all but a shaving or two of the waste. Either way will get you there. There are lots of ways to skin these cats. ... Not that I like to skin cats or anything. ;-)

I have that same Crown saw. I also don’t like the barrel type handles, which is why I don’t care for the Japanese saws much. I think the ergonomics of those handles are bad the way you have to have your hand twisted forward and down when holding them.

On an unrelated note, I got the LV plow plane like you have and am about to try it out for the first time. I need to use it to make a small frame and panel.

Keep up the good work and even better attitude.

-- johnjoiner

View Thuan's profile

Thuan

203 posts in 2569 days


#10 posted 04-17-2008 08:42 PM

This video simplifies things quite a bit

-- Thuan

View teenagewoodworker's profile

teenagewoodworker

2727 posts in 2519 days


#11 posted 04-17-2008 09:22 PM

well i don’t know much about the saw but for the dovetails if they are tight when you put them in and you have to wiggle them to get them out you will be compressing the wood. I heard Somewhere thought that the compressed wood will swell when the glue is on it which is the same idea behind biscuits and the newer dominoes. you might want to check on that first though as I’m not sure if its true.

and by the way where did you get the fret saw. I think that is would be easier when making guide templates for inlays to use that than a coping saw.

View Betsy's profile

Betsy

2914 posts in 2647 days


#12 posted 04-18-2008 03:07 PM

Thanks guys.

TAW——I got the saw at Woodcraft – about $23.00. It takes pinless scroll saw blades.

Thuan – thanks for the video!

-- Like a bad penny, I keep coming back!

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