Order Confirmed!
Cant wait to get this up and producing!
Thank you all again for your help!
Any suggestions on linkages for the router sled?
@pillageTHENburn 's linkage is looking VERY tempting!
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I’ve been setting up one of @dlang’s top-mounted pantograph linkages. Well made and it fit nicely into an open space on my sled. I could wish the chain attachments were easier to attach and unattached, though. An opportunity for me to add a personal touch 
Whichever one you choose, give thought to how to make the support pillars sturdy and accurate. Having the fasteners in exactly the right place at the top of the pillar, rather than at the bottom, is important.
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both linkage kits work well, the wood one is $30, the metal one $40
The wood one needs to be glued together, the metal one doesn’t
the wood one is easier to detach the chain from
the wood one has more predictable errors (but in both cases the errors are very
small, and far lower than the stock system)
I’m obviously biased (I wouldn’t have made the metal one if I didn’t think it
was better than the wood one 
)
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There is more stress on the pillars for the wood kit than for the top-mounted
metal kit (on the top mounted metal kit, the stress is passed through the links
and the pillar block vs the 45 wood kit where the stress is passed through the
sled)
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They definitely both have advantages and disadvantages, @dlang already mentioned the most obvious and critical ones. If you’re using the suggested Ridgid router then either linkage will work great. If you happen to have a much larger router then the top-mount approach has big advantages.
Like David said they both have very little slop/error, the biggest difference in that regard is probably the way the slop reveals itself up: for the 45˚ design any slop runs parallel to the chains and can be effectively cancelled out when calibrating (because the slop only changes the distance from the bit to the chain tip, but not the shape of the arc the chain tip traces). Any slop in the top-mount design ends up adding together (because joints are under both compression and tension) this can move the arc that the chain tip traces slightly higher and it can’t be easily removed with calibration. I don’t think there has been very extensive testing yet but it doesn’t appear that even this kind of error is super bad.
@MeticulousMaynard has a top mount linkage that he’s using (I don’t know if it’s one David made or if he made it himself) so he might be a good person to ask if you have practical questions about a top-mount design. I know he was experiencing some inaccuracy problems at one point and he is excellent at documenting his results so he’d probably be a wealth of knowledge.
I happen to be a little biased too but probably not in the way you’d expect… I actually really like the top mount design a lot; I like the look and I like that it gets way out of the way and it’s also just really cool! In fact it’s one of the very first designs I tested when I was originally working on the linkage concept in general but in the end I could not personally get comfortable with the compounding error problem so I decided to pour my energy into the 45˚ design because I could wrap my head around errors easier (and I knew how to account for any that would show up). David did an excellent job designing and cutting the parts for the top-mount kit too! With that said, I have not had an opportunity to assemble mine yet to try it out in person. So all of my experience comes from early wooden prototypes, so take that for what it’s worth.
I think you’ll be happy either way.
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Isn’t it the same amount of stress just distributed in a different way through the system?
Are you referring to the fact that in the top-mounted design the forces from each chain effectively pull directly on each other and the sled and router simply hang from the end, while the 45˚ design spreads those same forces around the router through the sled itself?
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Yes, in the top mount kit the bars pull against each other directly (or to be
more precise, through the bolt connecting the two sides), leaving virutally none
of the chain tension to be passed on to the sled through the pillar (just
what’s needed to move the sled, none of the competing tension)
While with the 45 design, the pillars have all the chain forces applied to them,
and so need to be very ridgid or any flex they have translates into errors
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I bought mine from @dlang. It’s been working pretty well for me so far, although I think that my performance is going to be worse than if you follow his instructions instead of going off the rails like I did. I still need to figure out a better hardware setup than I’m currently using because it’s introducing errors into my linkage system. See the top mount thread for more details.
I plan on buying one of @pillageTHENburn’s kits and doing some comparisons at some point.
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You might want to look at the “mostly printed CNC” machine, or the related “lowrider CNC”, for something in between Maslow and a ShopBot.
Also, just wanted to give you encouragement about starting a business. There is this idea that you have to go “all in” with a business, take out a huge loan, work for nothing, and years later, hope that you pull a profit. This is not the only way to run a business. Check out http://popupbusinessschool.co.uk
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