portable handheld mortising jig "build blog" #5: the lapping of slides and start of front fence assembly

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Blog entry by hobby1 posted 10-15-2013 02:44 PM 1488 reads 0 times favorited 9 comments Add to Favorites Watch
« Part 4: the finalizing of the dovetail slides, and prefit everything together Part 5 of portable handheld mortising jig "build blog" series Part 6: starting the front fence system »

I got a couple hours in yesterday afternoon, I started by lapping in the central dovetail block into both the subassembly guide rails, and the base guide rails, respectively,

here is one side of the block without any lapping done to it, it is rough on the top inside of the dovetail, this could have been prevented if I would have taken light cuts on the mill, however. I knew I would lapp this in, so I took substantially deep cuts, around 0.200” at a time, so the reason for the roughness.

here is the lapping compound spread onto the dovetail of the central block, I just apply very thin film of it

Here is the after lapping of one part of the block,

everything is smooth sliding, with little play, there will always be some play with this kind of sliding joint, due to the need for extreme ease of travel, by hand pressure, ususally for a dovetail slide, you want it to be almost zero play, which is where adjustable gibs are used, however, with that, you then need to move the slide via mechanical means, usualy a screw thread, because of the snugness of the sliding joint.

If I wanted a very good sliding fit with zero play I would have gone the rout of using a round bar and reamed bearings.

Now it’s time to start the front fence assembly

when I placed the guide rails on the base plate, I wanted some extra space to put a substantially long support block in to stiffen the fence front with the base plate.

So after some measurements

I can start making the two support brackets.

need to check to see how it fits in with very little gap on top.

now the marking off and machining of both blocks together as one piece.

and cutting it into two pieces for each side.

and a quick check for fitting in place.

Next is to attach these blocks and the front fence, then start working on the depth fence, for holding down the jig tight to the workpiece for edge mortising.

A few hours of shop time at a time, but it is coming together a little at a time.

have fun in the shop.

9 comments so far

View stefang's profile


15881 posts in 3356 days

#1 posted 10-15-2013 05:11 PM

Hi Hobby1. Nice work and a great blog.

I think I am finally onboard with this build, though I haven’t yet figured out exactly how it will work. The sticking point for me is how you will anchor (or not anchor) the slider part to position your router bit and then actually route the hole. I will until you are ready to show how it works. I’m just having fun trying to figure it all out.

I have a horizontal mortiser on my combo machine which has and XY movement table with clamps to hold the workpiece which travels back and forth and in and out using levers for each direction. It also moves up and down of course, but not while mortising. It is actually a great machine but it has one big weaknesses. The mortising bit runs counter clockwise because it is just a shaft mounted on the planer cylinder with drill chuck, so it has to be specially made to cut in that direction, which means it is difficult to find different size mortising bits for it.

-- Mike, an American living in Norway.

View jap's profile


1251 posts in 2076 days

#2 posted 10-15-2013 07:02 PM

great work so far

-- Joel

View hobby1's profile


335 posts in 2320 days

#3 posted 10-15-2013 08:18 PM

Hi Mike,
I think when I start working on the next parts, it will start to click in like a puzzle, I’ll not explain it here, so you can enjoy the build with the ciuriosity, once you see how these next parts attach to it, and how it all works together, it will be very clear.

I could give some good examples with commercial products but that would give it away to quickly.
I should say, my design of this is not my design, as far as the principle of its workings, just my design of how to use the materials I have on hand to make these principles work.

Thankyou very much.

Have a great day, everyone.

View David Kirtley's profile

David Kirtley

1286 posts in 3020 days

#4 posted 10-16-2013 01:24 AM

If the aluminum dovetails are too sticky in use, you can also set them a bit wider and add a gib strip of brass or UHMW polyethylene as well.

I had started a z-axis for a CNC router that was similar but I dumped it for a different design when it didn’t move as smoothly as I would have liked.

There are a few of us here that do metal work as well. I have been doing that almost exclusively lately.

-- Woodworking shouldn't cost a fortune:

View hobby1's profile


335 posts in 2320 days

#5 posted 10-16-2013 03:16 AM

Yeh, dovetails seem to be good for compound slides that are mechanically moved, especially with a leadscrew, or gearing, or levers, because to get the best running fit, gibs are the best choice, however, I opted to go with this for the simplicity of the build, if I went with gibs it may make it more difficult to move easily by hand preasure alone, if this design doesn’t work smoothly, then I’ll have to rebuild it by making sets of linear bearings out of round bar, and using it on round bar rails.

Thats what I ended up doing for my tapering jig for my lathe, I started out with dovetails and gibs, and a leadscrew, but I had too much play for getting the fine cuts on the barstock for the taper cutting, so I redesigned it to have a set of round bar rails and made linear bearings, like the principle working of a inkjet printer carriage movement.

View David Kirtley's profile

David Kirtley

1286 posts in 3020 days

#6 posted 10-16-2013 01:50 PM

I have pretty much wimped out on rails. They are selling rails so cheaply on ebay that it is hard to justify the use of my limited spare time. How come we don’t have pics of the tapering jig? :)

I am anxious to get started in my shop. We are finally starting to get some cool fronts coming in that will make the garage bearable. Not much gets done there in the summer.

-- Woodworking shouldn't cost a fortune:

View hobby1's profile


335 posts in 2320 days

#7 posted 10-16-2013 02:25 PM

This is not a woodworking lathe tapering jig, I made it for my metal lathe, mainly to machine morse tapers, to make tooling for my mill, and lathe.

I did use the jig to make a 1MT mandrel for my wood lathe to hold a small wooden wheel, to do decrorative round overs on, because the wheel was to small to use with a router bit.

Here is the jig:



View David Kirtley's profile

David Kirtley

1286 posts in 3020 days

#8 posted 10-16-2013 03:33 PM

Cool, looks like you have been busy. Nice work on the engines.

-- Woodworking shouldn't cost a fortune:

View hobby1's profile


335 posts in 2320 days

#9 posted 10-16-2013 05:09 PM

Thankyou David.

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