pumelloman,
Don't worry about the tapped holes in the conduit, or the spreading channels. Mine has been running for about a year with no problems with either. I did use steel tubing for the rail and gantry supports, which might have made a difference. I also used allen head bolts instead if hex head bolts to hold the conduit in place.
It seems by some tests I have done here, that people having problems with the above are tightening the bolts a lot tighter than needed, since very few people will be using a torgue wrench to tighten them down. When tightened properly, not 'tightened till the bolt won't turn no more', and using lock-tite, mine have not budged or moved in a year. Tighten them till they are firm, and they will not go anywhere. My test showed that when using a wood frame, it feels looser at the same torgue settings than it does using metal supports. Flattening out the top of the holes, so the washer doesn't have to bend will also help tremendously when tightening them down. That give as the washer is bending is very deceiving on how tight it is.
You will find that David's designs are the best out there, from my experience. They work well when built as described, but lend themselves to upgrades VERY well. His design would make a great all metal machine, with 4 or 5 start lead screws, solid rod instead of conduit, etc. is just depends on what you want to spend, and your building skills. I have been slowly upgrading mine as it makes me money. As time goes on, I'm sure it will be an all metal, kickass machine, that grew as my uses (and spending) dictated. Most other designs wouldn't do that very well. I'm sure if money were no object, A shop-bot or equiv would be great, but knowing me I would have went the Mechmate way then, for the building experience.
Good luck..  |