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Dovetails , Are They Really This Easy ?

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bosephus

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#1
and the answer is ... yes and no .

one of the biggest reasons i wanted a shaper was to cut dovetails without having to buy rather expensive cutters .
so today i decided to see just how hard it was . turns out that it is a rather simple thing to do .
all it took was rotating the ram around to 60 degrees , setting up an indicator and grinding a tool .
setting the machine up and doing the actual cutting was simple enough that just about anyone with some patience and an iq of at least 70 could do it .

grinding the tool on the other hand requires a bit more thought and finesse . on my first tool grind i seem to have given no thought to tool clearance . thinking that i wanted a 60 degree dovetail so i should grind a 60 degree tool .
wrong ! ... on the first pass with the tool i quickly learned my error . having a 60 degree tool in a 60 degree dovetail means that the entire edge of the tool is in contact with the work . and to further complicate things once you hit the inside corner you now have both sides of the tool trying to broad nose across the work .
not good !

so back to the grinder i went and ground the tool to roughly 55 degrees and gave it a bit more rake maybe 10-12 degree's and started cutting again .

eureka .. semi success . i haven't decided yet what i need to tweek on my tool because i did get a bit of chatter but im sure i'll figure it out soon enough .

with grinding the tools and setting up the machine this took about 45 minutes to do .
considering that i am using the drill press vice that came on the machine i decided to not worry bout being precise and just cut a basic dovetail to prove to myself it really is that easy .


20161212_163638.jpg
 

barnett

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#2
I haven't tried any dovetails yet, did you use the tool you ground to remove all the metal, or just the dovetail portion ?
 

bosephus

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#3
i used it to remove all of the metal , but if i was working with steel instead of aluminum or working on an actual project i think i would rough everything in as much as possible and then go with a finish tool .

i went out after dinner and made the other half of a dove tail . i started out with the intentions of trying to mate it with the other piece . but soon after starting it i realized i had goofed my set up and didn't leave enough tool clearance to make it match , so i cut it wide enough to fit the tool in just for the sake of practice .

tomorrows project ... both halves that fit together


20161212_210629.jpg
 

FOMOGO

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#4
Sometimes just getting started is the hardest part. Kudos for diving in. Mike
 

Ulma Doctor

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#5
congrats bosephus on the new bundle of joy!
you'll have hundreds of hours of fun! :grin:
 

bosephus

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#6
Thanks guys .

Hundreds of hours of entertainment may be an understatement .
and not only will it give me untold hours of fun , it will help me finally get my little brown and sharp milling machine going properly . my only road block with it has been needing a way to cut the proper size key way in some cutters .

The first thing on my wish list is a proper vice , quickly followed with a clamping kit .
While I'll probably buy a clamping kit first simply because it's a bit more affordable .
I would be very gratefull for some suggestions on a proper vice for the machine .
would something around 4 inches be an appropriate size ? something I could use on both the mill and shaper sure would be super fantastic .
 

bosephus

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#7
Would it be considered greedy if I asked Santa for a dividing head and tail stock .
 

barnett

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#8
Does the table on your shaper have t slots, mine doesn't have t slots, but the table on mine tilts both directions r & l. The closest i could figure, mines a Lewis kit. The table ratchet is on the opposite side.
 

barnett

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ndnchf

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#10
Good discussion. I've not tried dovetails on my 7" Ammco either, but would like to. Can you post a nice clear photo of the tool you ground? Thanks
 

Billh50

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#11
Would it be considered greedy if I asked Santa for a dividing head and tail stock .
He just might, ya never know. I know he never gave me the real mill I have been asking him for. But it may be because it's too big for his sleigh to carry.
 

Reeltor

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#12
Congratulations, the dovetail looks good from here.
 
F

f350ca

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#13
Congratulations,
Try going with even less angle on the tool, you only want to be cutting at the tip with clearance on both sides. A bent tool holder will help, the shorter you can get the cutter the better.

Greg
 

bosephus

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#14
barnett , yes it does have t slots . three slots on two sides .

ndnchf , once i get out to the shop this evening i'd be very happy to take a pic of the tool . but i can not make any guarantee as to clarity i'll do my best .
i dont own a digital camera , what pictures i do take are from a very dated cell phone .

more clearance hmm ,.. i'll give it a try . tool rigidity ( is that a word lol ) was one of my concerns and also was what caused my goof on the second set up .
it makes me wonder if for general use it might be better to try mounting cutting tools directly into the tool post when ever possible and only using a tool holder when absolutely needed .
to my thinking there would be a couple advantages to that .. less flex without the tool holder and the ability to use bigger stiffer tools .
its something to think about .
 

Jim2

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#15
With regard to larger toolbit directly mounted vs. using a toolholder to minimize flexing, there's another option. If you're using a shaper tool holder instead of a lathe tool holder, any flexing will cause the toolbit to come out of the work rather than dig in. It all has to do do with where the toolbit is in relation to where the fulcrum is. Check out this picture

IMG_5002_zpses8dzofh.jpg



The toolbit is back far enough that it doesn't dig in the way it would with a lathe toolholder. I was very pleasantly surprised how much easier it was to cut dovetails without chatter when I started using this tool.

There is a downside in that you do need a little more clearance on the toolbit, otherwise it can dig into the work on the return stroke. I had that happen on this workpiece.

Marks-001_zpscnq49poe.jpg



You can see scratches that were caused by the backside of the toolbit on the return stroke. I also notice that I need to lock the downfeed as it tends to feed itself using the shaper tool where I had never noticed that with the lathe tool holder.

Jim
 

bosephus

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#16
Ndnchf.
Unfortunately I never got a chance to get out to the shop , it started snowing like heck here and I spent the afternoon playing taxi cab and designated snow shoveler. The cold takes a lot out of me and makes the arthritis rear it's ugly head .
Jim2
Your tool holder makes a lot more sense to me for a shaper then the lathe style . A lot less leverage going on there
 

bosephus

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#17
todays plan .. dovetails version 2.0
i have a fire going and once things are warmed up i am going to try for dovetails that mate .
i think this is gonna be a challenge without a proper vice ... but i feel up to it
 

cjtoombs

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#18
Jim2, the gibs on the shaper downfeed should be kept fairly tight to prevent the falling tool issue. If you leave the gibs too loose, the toolhead will slide down on the backstroke and then slam into the work and ramp up to take up the backlash. Why it didn't do it with the lathe tool is a mystery to me. Tighten the gibs until you are uncomfortable with them, that's about right.
 

MetalMonkey

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#19
Bosephus,

Did you ever get a matching set? I'm the brand new owner of an SB7" and looking for inspiration and future projects to try. Dovetails are on the list!
 
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