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Parallel Guides

Jeremy Wright
Thu, 14 Jul 2016 20:08:57 GMT

A couple of questions on parallel guides: --Pinless "Maguire" / Linear bearing: Has anyone used this system and have any tips? I like the looks of this and I know Richard wouldn't support it if it didn't work, but I'm curious about these ball bearings and longevity in dusty environments. Also the install process seems like it might be fiddly and I've not found any solid documentation yet. --Traditional Pinned. Because of the twin tenons in my leg (see background) I need to offset this to one side, otherwise I might be overly weakening the leg. Does this present any issues? Placing above/below the rail, cutting a bridle joint below, seems like it might weaken the leg (especially if offset.) I'm probably overthinking this. Background: I've been working on a duo-slab split top Ruobo (for an inexcusably long time) and am coming up to the leg vise install. I am building the bench (over on Instagram #MORBP) from a tree felled on my property and am working not from plans but from what is available, fits and looks "Wright". This has introduced some complications as earlier design decisions flow downstream. In the "leg frames" I used twin tenons, in part because a single tenon appeared too short, also joinery is fun. I didn't completely think through how these leg frame mortise would influence the leg vice later on. Likewise I wasn't 100% sure on the height, and now the placement of the lower rail is exactly where I'd like to place the guide. I bought the simple LV tail vise screw for this purpose, and I think this will work as needed. I did consider the Benchcrafted Classic with criss-cross (To freely admit my sloth, the screw was sourced when BenchCrafted was only just starting to make hardware...) The criss-cross is not really a viable option given the amount of material removed will be bad in the joint area given the way I have the mortises arranged.

Tue, 19 Jul 2016 03:50:08 GMT

Jeremy, For the leg vise on my Roubo I went with the (Maguire type) pin-less shaft system. I bought a 30mm shaft and its matching linear bearing off Ebay. As far its operation goes, I think “buttery” describes it well. Combined with the Benchcrafted classic vise, it glides in and out effortlessly. I’ve been using it now for around 6-7 months and haven’t had any issues with dust getting into the bearing, even with it sitting 4 feet behind my dust collection-less table saw. The rubber flanges on the bearing seem to do a decent job at keeping out even fine particulate. That being said there are certainly some problems to look out for during install. Firstly, try to get a shaft bearing with a housing diameter that matches a bit you have, or plan to buy. The housing on mine was in metric which didn’t allow for an even conversion to my standard drill bit size. Because the hole for the bearing drilled slightly larger, it can flex a little bit. And this flex might require you to make adjustments to your chop angle. To overcome this, I made sure the bearing was seated on the bo ttom of the hole before I screwed it in place. Now the shaft diameter itself should also be taken into consideration for the same reasons… The one I used was in between bit sizes. To fix this, I put a rat tail file in a drill, and bored out the hole just a bit. It worked, but was kind of sloppy and now the shaft has moved to the point where it’s no longer angling the chop inward. You might want to, simply, drill the shaft hole perpendicular to the chop and taper the chop itself to provide for the needed angle. This was the other option Benchcrafted suggested in the instructions. If you do decide to drill an angled hole I think I installed the shaft with an angle somewhere around 3 or 5 degrees. Another thing to watch out for is the thickness of your chop material. I used an 8”W x 2.5ish” thick piece of mahogany and it can still flex under serious vise clampage. Even with the current issues I’m having (of course all self-inflicted), the vise works well. It gives a tremendous amount of clamping pressure. Over the next few months I plan on taking it apart and fixing some of the problems. Hope this helps and let me know if you have any more questions or would like to see some pictures.

Jeremy Wright
Wed, 27 Jul 2016 16:58:03 GMT

Thanks Gallywack! useful information for sure. I have decided to go this route as well and have most of the parts on hand, but am still waiting on a couple parts & bits before digging in. How did you fix your shaft to the chop? I am assuming epoxy, but am a bit concerned about the permanence there.

Scott Nichols
Wed, 27 Jul 2016 17:20:23 GMT

My plan is the third option, the chain leg vise: http://lumberjocks.com/reviews/3065 (http://lumberjocks.com/assets/pictures/reviews/343943.jpg) But I plan to roll my own chain hardware.

Jeremy Wright
Wed, 27 Jul 2016 17:38:20 GMT

Looks interesting, please post updates along the way. I seriously considered that, and was thinking about using a steel cable (like on an old parallel bar drafting table) since the chain is loaded in tension when clamping, but might need a larger diameter roller than the chain requires. In the end, I decided to act now rather than delay with additional design time, The Maguire pin-less style also has the advantage on fewer (off the shelf) components.

Josh Doran
Thu, 04 Aug 2016 17:33:04 GMT

Hey Gallywack. So how is the shaft affixed to the chop? I never heard . Epoxy like Jeremy suggested? I've been pondering this problem myself. Or maybe a way to pin the shaft into the chop if you can drill through the shaft (probably too hard, I'm guessing)