Thread: Rob Cosman Saw - How it's made

Interesting. Up to now I had assumed he used the 'plastic' handles because they were moulded, but my ignorance has now been enlightened. I guess the material they use is a lot more consistent and lends itself to their shaping machinery better than most woods.

I do some saw-making steps similarly, though on much less of an industrial scale! My drill-press slot cutter is far more basic, but remarkably similar. I noticed he cut his slot in two passes, whereas I cut mine in several, just a couple of mm at a time. If I try to cut too deeply in a single pass, the slot starts curving, which I presume is due to the blade overheating & warping. He must be getting a bit of that effect, as he made a point of checking to see which end was more 'centered' after he'd finished.

It seems like gross overkill to me to use adhesive and rivets to hold the blade & spine together. A press-fit spine does a perfectly adequate job, & I cannot see that all that extra fixing contributes anything to the saw's action, but maybe I'm missing something. I would like to read the saw review in FWW, but stopped getting it a while back, so will have to find a copy somewhere...

I have only used a Cosman saw once, briefly, and I thought it was a good little saw, apart from the too-high grip angle for a dovetail saw (imo, others clearly find otherwise!). It was 15tpi, which is my favoured D/T saw pitch, and I think had a bit more negative rake than I use, which gives it a less aggressive & 'softer' action. But they don't come cheap, do they? I guess when you see the amount of work that goes into a 'hand-made' saw, you understand that anything less yields a pretty miserable hourly rate.

Cheers,

Yes, I had assumed the handles were moulded also. I think the blade is pinned because the slot is too big for a friction fit. Despite the production line of equipment there is still a lot of manual fit and finish.

I wouldn't swap one of my new saws for a Cosman.

I have been using Rob Cosman's DVD to teach myself dovetails. Having seen a lot of his videos I am pretty sick of his 'you need these best tools (read: my tools) to do this well' attitude. I just assumed he'd organised someone to make them for him.

However after watching the video, I see he actually makes them himself. Thanks for the link. I've got more respect for him now.

Originally Posted by Pittwater Pete

I wouldn't swap one of my new saws for a Cosman.

Why not, Pete, maybe you could flog the Cosman and buy a few more saws.....

A couple of observations I'd make on the current high-end crop are:
a) It would seem that the steel for most if not all of these saws is the same stuff (1095) and while there may be some slight variation in temper from batch to batch, it's unlikely any of us could pick any difference in the metal.
b)A saw will need sharpening at some point, so unless it goes back to the original maker, its performance will from then on be determined by the skill, or lack thereof, of the sharpener.

So it really boils down to choosing a saw that has the right size & tpi to suit what you intend doing with it, & feels 'right' in your hand. If it also looks good to your eye, that's an added bonus.

Cheers,

Interesting. The handle material comes in lots of colors too. Sorrel, rosemary, burled beech and deep space are promising. Colors of Corian® | DuPont | DuPont USA

I came across this 2009 thread from the Sawmill Creek Forum site;

The sidelines were killin' me so I had to sign up to speak up! Many thanks to those "Brave" souls who ventured away from the norm to buy a saw! For those that have to own more wood, buy a Gramercy or a Wenzloff, Joel and Mike make beautiful saws. I have a couple on order. You will have to wait ‘till he catches up however, he’s not taking any more orders at the moment. You can buy a LN if you can find one. After spending 8 years distributing for them in Canada and living thru "Painful" months of back ordered saws I care not to live thru that again. You also have the option of ordering from any of the other very good wood handled saw makers however you may find the same waiting period there.

My point... I teach folks to cut dovetails for a living, amazing as it sounds that someone could earn a living from the way two pcs of wood are joined at right angles! Be that what it is, (very enjoyable I might add) when I fly to a Woodcraft store and teach a dozen or so enthusiasts the craft, they get excited and want to rush home to ply their new found skill. On the way out they go for the "then promoted" LN saw only to find there are two on the shelf and twelve grabbing for it. A quick check on the inventory computer gives the bad news that the item is back ordered for another month and has been for several months.

It didn’t take long to discover the problem, you can’t shape a nice curvy wood dovetail saw handle on the router or CNC without a lot of the curves gone missing, read "grain direction"! So in happy town Maine several local workers carve and sand away on maple handles. Tom is fussy and I applaud him for this, problem is that when someone sneezes and accidently takes off a nice neat corner of the almost finished handle it becomes fodder for Tom’s woodstove and we start again. The handle is the bottle neck for everybody and of the few that I have seen try to simplify it I would not want to own one, read "UGLY".

My handles are a composite, think of Corian with glass fiber added for strength. We get the material in 7" strips 1" thick and bandsaw, rout, drill, sand and buff to the final state. It is heavy, strong, water proof, no finish to wear off. Those with that "acid" sweat will know what I mean. If you drop it, like wood you will damage a sharp corner, there are limitations.

Having taught so many to cut dovetails I wanted to level the playing field as much as possible. I love the wizards who proclaim from the mountain tops that "it's not the tool", to them I say show me your work and let us decide. Every profession that needs them have professional tools, several notches above what the consumer gets to buy. I stand by what I have always said and as many times had to prove, cutting dovetails is 70% the tools, 20% the technique and 10% practice. Look at Gray’s dovetails if you need proof. He came into my class having never cut a joint, used good tools and his first 1/2 blind was as good as mine. I might add that out of 9 students in that class three of them were as good as mine. (Don’t sweat honey I am still faster!) (That always makes her worry)

Gary is one of many, sooner or later I will get a page on my site devoted to first timers. If your thinking it don’t say it, Gary's first was as good as the last 400 he has shown you here, he's just a lot faster now. Kudos Gary!

So back to handles, surgeon saws were a good example of what can be used, bone, ivory, mother of pearl, wood. I'd still love to have an old peace maker 44 with ivory grips.

Bottom line, I am making saws for those that want to learn to cut dovetails expertly and do it now. The demand has already got two and 1/2 of us working late into the night so I don’t think we have to capture all of the market, a percent or two will be just fine.

A quick note on the other features, biggest is the small teeth up front. Not seen this done before and in searching patents no one has ever registered it. Hard to believe something this effective went by undiscovered and as I say that I know it was probably used, loved and forgotten only to be revived at a later date. I learned from Alan Peters that most of the best tips and techniques were well guarded secrets that often went to the grave with the craftsman. The weight came by accident but I really like it and when I pick up another saw it feels like a toy. That said, if this one tires you out it may be time to renew that gym membership! Copper pins in the brass, hated that saws were only glued to the brass. In the past I only ever saw a few come loose but the copper pins will fix that from ever happening to mine. The longer blade makes for longer strokes, longer sharpening life and easier to use. Narrow set, this is something I use to do to the LN saws I sold, less set, better tracking, and smoother sides. You can hear the difference, think smooooooth! The fancy box was our way of presenting filet mignon on china, a paper plate just doesn’t do it. We take it in the pocket for this one, the price of the saw is just that. I have beat up other saw makers for not charging enough. How many of you would do the work you do for poverty wages. From the start I planned to run this as a self sustaining business, the boxes are the last carry over from my woodworking days. Read that as woodworker 101- tell the customer every mistake you made and then apologize for the price you charged them, even as you take the next deposit to pay off the materials from the last job. There will only be a few of you that appreciate this last statement, we share a brotherhood of Pain!!

Back to work!
Cheers,
Rob Cosman

Rob Cosman Dovetail Saw - Sweeeet!!!!!!

Stewie;

Nice find. Probably worth linking in this too.
Explains why he didn't say much about the blade in the video. Secret.
Rob Cosman

Originally Posted by hiroller

.... Explains why he didn't say much about the blade in the video. Secret....

Beats me what's so 'secret', Dale. The saw I tried looked like a pretty standard saw blade. It seemed to me that the rake was quite laid back from the way it cut, but with my age-challenged vision, I couldn't even guess what the angle was. I happened to have one of my own saws with me, same tpi, and a rake of -7 degrees (I do know that! ), and it cut significantly more aggressively in the same piece of wood. Perhaps that's the 'secret' - since he spends much of his time teaching beginners, they'd probably find a more laid-back rake easier to start and handle than one of my D/T saws?

Cheers,

Originally Posted by hiroller

Nice find. Probably worth linking in this too.
Explains why he didn't say much about the blade in the video. Secret.
Rob Cosman

Rob Cosman; A quick note on the other features, biggest is the small teeth up front. Not seen this done before and in searching patents no one has ever registered it. Hard to believe something this effective went by undiscovered and as I say that I know it was probably used, loved and forgotten only to be revived at a later date.

Daryl Weir's reply; Hello Rob,

Nice looking and interesting saw! I don't post here very often at all but this thread looked interesting since it involved a saw with a little bit of a new twist to it. You talked about never seeing the small teeth up front before but here's a picture of a high end Disston No.77 no-set saw from a 1914 catalog. I know these are shown as cross cut configuration but I'm sure they could be filed in a rip configuration also. I realize the ppi is coarser on these but the principle is the same.



Rob Cosmon; (no reply)

I did have chuckle when I read this;

We found a small father and son company in Tiawan that now makes our nuts and bolts, the quality is better than what we were getting locally.

Fascinating.

No I don't need extra pix on that first post. I made the mistake of clicking too quickly the second time and the "likes" had moved on me.

Regards
Paul

I think that rake angles bear some discussion - I've found that relaxed rakes are preferred these days rather than the 4^o rip and 8^o crosscut angles of received "wisdom".

Originally Posted by rob streeper

I think that rake angles bear some discussion - I've found that relaxed rakes are preferred these days rather than the 4^o rip and 8^o crosscut angles of received "wisdom".

OK Rob, I'll kick it off..

The figures you give are a bit higher than I prefer (which are more like 7 and 14), and I am on the side of somewhat more 'aggressive' angles round here, it seems. Perhaps that's an indication of the harder woods we deal with down here.

My theory, which I've put forward a few times, is that a person new to sawing will find a more relaxed rake easier to manage on a rip saw, & particularly if you regularly saw very hard woods. The slightly slower cutting rate won't bother them, because if they've not used a 'decent' saw before, it will still be a revelation in how quickly it goes, yet still be easy to start & have a smoother action. In watching inexperienced saw users (& I also remember my own early struggles at making a saw eat wood the way my father could!), I'd say the universal 'mistake' is forcing the saw, i.e., putting too much pressure on the cutting stroke. Dial in a good 'bitey' rake angle and you have a recipe for rough, catchy, sawing and a disappointed saw user. So for rip saws it makes sense to ease off the rake when the bulk of your market is likely to have little experience of hand saws in general. At least compared with the saw buyers of 100 years ago.

However, while that may be a plausible theory for rip saws, it doesn't apply so well to crosscuts. This tooth pattern is far less sensitive to rake angle, it's the points that are doing the bulk of the work. Instead of 'chisels' scooping out the wood, we have tiny knives cutting the fibres. The more shallow the fleam angle, the 'sharper' the knives (but with a more delicate edge), while a more laid-back rake angle gives more of a 'slicing' cut (like slewing a plane). But I've found you have to change the rake by quite a lot on a crosscut before you notice a difference, they are far less sensitive to a few degrees one way or the other compared with ripsaws. So rake angles between your 8 and my 14 won't be as noticeable in softer woods, but you will certainly notice a difference in very hard stuff.

In the old days, when most tradesmen sharpened their own saws on a regular basis, they would have eventually arrived at a set of parameters that best suited their needs (if not by insight & logical deduction, at least by trial & error). So the message is, old hands can make certain recommendations and suggestions, but ya gotta sharpen a few saws for yourself, and see what differences you get by altering the various parameters, to find out what you like best....

My 2c,
Cheers,