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portable handheld mortising jig "build blog" #4: the finalizing of the dovetail slides, and prefit everything together

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Blog entry by hobby1 posted 319 days ago 639 reads 0 times favorited 5 comments Add to Favorites Watch
« Part 3: the determining and building of the guide rails Part 4 of portable handheld mortising jig "build blog" series Part 5: the lapping of slides and start of front fence assembly »

Hi guys Please:
If you get tired of all this technical stuff I’m showing here, please let me know, and I’ll just post the highlights of the build with much less play by play details.

The next thing I worked on was, assembling one set of dovetailed slide rails on the main baseplate, that will allow the router to travel in the “Y” axis direction.

Here I’m using again my surface plate as the datum, to ensure the fixed slide is assembled perfectly square with the front of its base plate which is sitting vertical on the surface plate.

now roughing in the size of the dovetails on the slides

I can layout where to machine the central (universal joint) dovetailed block, for its dovetails to mate into there.

I know I want to have alot of support with this central block, so I will need to machine the two ends down before I can cut the dovetails on the block.

So I marked out where the cuts will need to be,

Now before I cut out the end pieces for the dovetails, I want to machine the dovetails on the long side of the central block first, which will mate with the top router base subassembly.
So I couldn’t hold this in my vice, it needed to be clamped directly to the table, any time a new fixture is put on the table, be it a vice or the workpiece itself, you always need to clock it in, also known as, zero indicate it in, this is what I’m doing here, I’m lining up the workpiece to be accurately parrallel with the “X” axis of the mill table movement, so every thng is true and square with relation to the mill table movements.

now the dovetail milling can proceed.

now the next sequence of pictures shows the order in which these parts will mate together, and where they will finally be located on the subassembly, which was done in the first blog installment.

I am goint to fasten the fixed slide rail to the subassembly, by tapping into the subassembly plate itself, because there is enough thickness to put a screw into for good adhesion.
I need to find the thickness of this plate

so I can set the guage to half its thickness

which then allows me to mark the slide rail itself for a ref. line to drill the screw holes for.

with the rail predrilled, I can now transfer punch one of the holes to the subassembly, for drill and tapping a screw hole.

now I have to do the opposite with the next slide rail, because the base plate is to thin

to tap into for good support of the rail here I set the central block tight against the fixed rail which now alows me to position the adjustable rail where it may be, to know where to drill clearance screw holes at.



once the plate has clearance holes drilled I can transfer punch to the slide rail,

and drill and tap the rail

here is the subassembly mating with the central (universal joint) docetail block, this gives the entire router the “x” axis travel for the width of the mortise at each location on the board.

Now I can proceed to machine the central dovetail block on it’s ends to give the router it’s “Y” axis travel, which gives it the depth of cut of the mortise.

the next sequence of pics shows the central block being machined for the “y” axis movement of the unit.


The universal block to its base, for the “Y” axis travel

Every dovetail slide has some way of adjusting the tightness of the slide to its mating piece, to reduce unwanted play, usually a gib is used, or a slot is cut in the divetail itself to be used as a fised gib, these slides are not going to get a lot of wear and tear to need constant adjustments, so no gib will be used, however, there is always the need to lap in mating sliding parts to give the best sliding fit possible with very close to zero play, between them, so I am making one slide rail of each set fixed, and its partner an adjustable one, by elongated the screw holes into slots for making final adjustments.

That was the bottom plate, being machined, the top subassembly needs the same treatment, later on.

When I do the final asembly of the entire jig, I will use lapping compound and lap in the mating slides, then loosen the screws on the adjustables, and move them in tightly until the slide block is pinched, and again lap it in, until the slide block is so lapped in that no excessive play will show with the slide block and both sets of rails, yet they need to move in there respective coordinates very easily which is side to side, and in and out, to produce the mortises.

Here is everything mating up as a dryfit


Next after some final tweaking of this stage, I can start working on the fence system, that will involve some careful laying out and measurements as well.

You guys said you enjoyed watching the machining techniques being done, so thats why I’m going into a lot of procedural details, to show this build.
Please as I write above:
If you are tired of all the technical stuff involved, please let me know, and I’ll just post the highlights of the build with much less play by play details.

Have fun in the shop….



5 comments so far

View stefang's profile

stefang

12947 posts in 1968 days


#1 posted 319 days ago

Personally, I like all the details, and if you are willing to take the time and the effort to photograph, write explanations and post them I will surely read them with great interest.

-- Mike, an American living in Norway.

View jap's profile

jap

1226 posts in 688 days


#2 posted 319 days ago

I love all the details, since most of it is new and fun to learn.

-- Joel

View hobby1's profile

hobby1

282 posts in 931 days


#3 posted 318 days ago

Thanks guys for letting me know.

View Mark Shymanski's profile

Mark Shymanski

5099 posts in 2346 days


#4 posted 289 days ago

Thank you for all the information. This has got me thinking about the possibilities….

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View hobby1's profile

hobby1

282 posts in 931 days


#5 posted 289 days ago

Mark,
Your welcome, I’m glad the information is helpfull.

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