Thread: Fixed width dovetail templates

When I opened the DXF in Draftsight, it shows all the round bits as angled lines,

Hey Bob What model CNC machine do you have?

Originally Posted by Bob Willson

When I opened the DXF in Draftsight, it shows all the round bits as angled lines,

I downloaded the DXF and it opened OK , ????
what other file extensions can you open , ive had problems with TurboCAD > DXF before , most the time the files wont open
its a 2D line , not a 3D model , ill 3D it and see if it opens better
DovetailJig7DXF3D.zip 5mm thick
if that dosnt open i can change the type of "object" , this one is a " solid " , not a"turboCAD solid"

?? try the EPS in cut2d / victric

Originally Posted by Bob Willson

Ummmmmmm, errrrrr, yes - my own thoughts exactly.

lol midnight dribbling ,might be very handy for the Mach3 wizard maker )

Originally Posted by delbs

Hey Bob What model CNC machine do you have?

The Bob Willson model. Cuts about 1500 * 850 using a 4hp spindle.

Originally Posted by SawDustSniffer

I downloaded the DXF and it opened OK , ????
what other file extensions can you open , ive had problems with TurboCAD > DXF before , most the time the files wont open
its a 2D line , not a 3D model , ill 3D it and see if it opens better
ry the EPS in cut2d / vectric

I tried to open the DXF in both DraftSight and also in Aspire. In Aspire it comes out as absolute cr@p, while DraftSight gave similar results to before.
So I tried it with EPS and got good results in both DraftSight and Aspire.
So, what you have drawn looks like it is getting there. It will also need an area that can be clamped/screwed to something to keep it from moving around as well

the other side is your 9/16th bit @ 14 deg , with cut depth set to 8mm . both sides are 1/2 wide dovetails ( line the 2 peaces up to the line , the L holes are for the front off set , raising the bit higher will over cut , and increase slop in the join , 0.5mm should be good )

DovetailJig8.JPG
DovetailJig8EPS.zip

Tha looks like a great jig Ken. Well done.
Now I need another one.

Would you mind doing one for this leigh bit (818-133-11) as well please and maybe a (818-129-11) on the other side.
These are necessary for slightly thicker timber up to 19mm thick.
Thanks Ken

no bearing size ?
133's cut length is only 16mm
as well as bearing size it will need depth of cut , and size of dovetail , could even make the dovetails wider ( work best with large angle) how long do you want the jig , you have 2 sides ,??? same bit same depth but double the width on one side ???
DovetailJig42.JPG
with these next ones ill add 0.2mm slop , probably best to say 1mm away from max depth ( bit length )as raising and lowering the bit 0.5 from its "set depth" will make it looser or tighter

### cant delete posts , a big cock up with that design , ends up a small gap is 9.8mm ( a 12.71mm wont work )

so any one who copied the " koala and rabbit ears " the koala ears wont work with a bit bigger than 9mm

Rather than use a bit with a bearing, It would be better to use a template follower in the router base.
I have a set of these from Timbecon, (Timbecon no longer seem to sell them, this link is to Lee Valley) the sizes are made to suit a variety of imperial sizes, but the one that Leigh uses for their dovetailbits is 7/16" (11.1mm) OD * 8.55mm ID. This is suitable for their 3/8" (8mm) shank and smaller bits.
Where possible, it would be better for the Koala and Rabbit ears templates to use these guides so that the depth of cut may be adjusted without fear of raising the bearing too high.

all you need is the bit the same size as the guide , so this jig will work with ,


up too 1/2inch on the rabbit ears
up too 3/8inch on the koala side
KOALANRABBITEARS.JPG
KOALANRABBITEARS.zip


images of the testing

KOALANRABBITEARSTEST2.JPG

KOALANRABBITEARSTEST1.JPG


with a 1/2 inch bearing , the difference between bearing / guide and bit could be a max of 4mm
at 4mm difference the pins will be 8mm wide , and easy to bend if knocked ,
so a 12mm bearing on a 8mm bit would be at the extreme end of the jig not handling a kick back , and bending a finger

you could use a bottom bearing bit , or place a packer between jig and job with a high mounted bearing

spent an hour tonight fixing the "above" template , to a better Koala ear shape , both sides can use a 1/2inch bit with 1/2inch bearing

KoalanRabbit2.JPG
KoalanRabbit2EPS.zip


trying to work out the set up

quote "Leigh uses for their dovetailbits is 7/16" (11.1mm) OD * 8.55mm ID. This is suitable for their 3/8" (8mm) shank and smaller bits "quote "

so the largest diameter bit to pass up into the guide is 8mm , so the jig ends up 10mm thick on the "Rabbit ears " ( the blue area is the bit and guide ,yellow is the 13.2mm jig )

test.JPG

i should be able to make the joint a lot smaller , at the moment its 26.36mm deep for the rabbit ears , but if i make the join smaller it makes the jig thinner , at a guess if i reduce the join too 22mm the jig will be 8mm thick , 18mm it will be 6mm thick , the smallest of 16.5mm ( 2 bits + gap" would make the jig 5mm thick , how thin would you like to go ?

3/8 guide with 1/4 bit might be better , i could go even smaller ,at 1/4mm + 0.5mm gap for clearance the jig would be 3.17mm thick , and overall joint size of 13.7 ( width of cut ) , for every 2mm the joint size go's up , the thickness of the jig go's up 1mm ,
so at a jig thickness of 6.5mm ( still thin ) the cut size of the join would be 20.36mm lol , no difference than the next size up ( if you can get 8mm bits )

a 10mm bit with 10mm bearing the joint size will end up 20.5mm with a 9mm thick jig fingers ( if you can get one )

i changed the rabbit ears on this one , they dont overlap as much , making them 24.63 wide , also the end grain wont be as bad , the ears are at 60deg rather than 90deg
same 1/2 inch bit with 1/2 inch bearing

KoalanRabbit3.JPG
KoalanRabbit3EPS.zip


and a couple more shapes
DovetailJigs9EPS.jpg
DovetailJigs9EPS.zip

Discussion in this thread has gone past this a bit, however here is a template I made some years ago for through dovetails.

Along the lines of Rockler, Porter Cable, Gifkins style. Matches bearing guided bits bought from Carbitool.

Used it quite a bit for small boxes and drawer cases.