Archive for May, 2012
I know it’s been a while since I posted … things have been crazy busy and I lost the urge lately….but, I think I’m back for a while. There are a couple of items that I have completed in the garage but haven’t posted about – this is to catch up on one of those and I expect some progress to be had to get this sucker finished soon.
When we travel afar for a regatta, it pays to double stack two catamarans on one trailer to save on gas and travel in bigger groups. Once the garage is done, one of my next projects is to modify my existing trailer so I can once again double stack by fabricating a steel rack with a second set of cradles above the lower boat to enable traveling with two catamarans at once. The dilemma is that getting the heavier F18 boat up on the elevated cradles is cumbersome and usually requires four strong, able, bodies. It’s not always easy to get the number of hands needed to load the boat since you don’t want to bring your whole team to my house for 10 minutes of loading – it’s been a problem in the past and I’ve probably used up all my favors with my neighbors for help when this happens. Unloading is easy because we are at a regatta with plenty of people around ready to help. Occasionally, I also have a need to lift other heavy things and it’s possible I could get back into customizing cars (I have this nagging desire to convert a Mazda Miata to an all electric commuter vehicle, for instance). I have a pretty heavy duty engine hoist but it can’t reach out enough to get to the center of a catamaran and it eats up floor space during the 99.99% of the time it’s not in use…so after a little day dreaming, I determined that a ceiling mounted hoist would add a nice convenience factor to the garage and I set out to developed a plan.
I started sketching out plans for a hoist and decided it needs to be able to move on a rail. I sniffed around at work and found a 10 foot long 4 scrap I-beam in great shape and bought it for the measly sum of $14. I already have an electric 500lb hoist that I picked up a year or so ago for about $50 from a guy who never used it and a visit to Amazon.com yielded a brand new $60 I-beam trolley designed for a hoist. Another visit to www.mcmaster.com found the pieces of 1/2 all thread, blind nuts, and tapered washers (to match the webbing angle of the I-beam) where I probably spent something around $50. $175 in and I should have all the items need…which is less than I think I paid for that engine hoist 15 years ago. The plan is to attach the I-beam across seven of the floor joists and it just works out that it will align almost perfectly with the bridging / box spine I put down the middle of the floor which will help to further strengthen the hoist. I got a few raised eye-brows from some folks about bolting a lifting hoist to a ceiling / floor structure – but the engineering is sound….At maximum capacity (600lbs), it’s very similar to the loading required to support two of my 250lb friends standing back to back upstairs – and I wouldn’t be nervous about the floor breaking if that were to happen. In fact, the loading is probably a little less since the I-beam loads will be spread out over several trusses at once (given some minor deflection).
The trick now was to get all of these holes aligned and drilled. I also had to figure out the sequence of installation with regards to the drywall and insulation and I also wondered if compression of the drywall when I tighten the beam might be a problem. Chances are that it wouldn’t be – but I developed a plan for both.
Step 1: Snap a chalk line to make two straight linear marks matching the width between the holes to be later drilled in the beam.
Transfer identical lines on several pieces of MDF board that will serve as a spacer between the joists and the beam and take the place of what would otherwise be drywall in that space but this won’t stand much chance of compressing. The MDF will also help me by making a template of the holes I drill in the joists to transfer to the beam.
After also marking the upstairs floor with the chalk line (between four pilot holes marking the ends of the series of holes), I counter-bored those holes to receive a series of thread-locking blind nuts (rated for about 1,000 lbs each) so they would be flush with the subfloor and not impeded the future floor upstairs.
The MDF was clamped in place, splice plates were stapled and glued in place to make it one long continuous 12 foot piece, and small pilot holes (1/8) drilled to mark the holes. Small finish nails were pushed through the holes to pin the MDF in place and ensure it didn’t move.
With the pilot holes drilled, I drilled them larger to receive the all-thread and started installing the all-thread through the entire truss to the blind nuts in the subfloor. Each end of the truss also received nuts with locktite on the inside span of the trusses to prevent the chance of overtightening the beam to the subfloor causing an undesirable compression of the truss system. This also helps to ensure that the entire truss system works and moves together in response to changing loads upstairs and down. The nut on the upper member of the truss is snugged up to help compress the blind nut into the sub-floor ensuring that it is engaged solidly with the wood structure without adding compression to the truss below.
Each piece of all-thread was cut to a different length with the longer ones on the outer most ends of the beam to allow gradual hoisting of the beam and avoid having to line up 14 holes at once! The all-thread will need to be trimmed to fit once the beam is home.
I apparently didn’t get photos of it – but the MDF was removed from the joists and clamped to the beam. Sharpened finishing nails allowed me to ping the hole centers through the MDF into the beam where I drilled the holes to align with the all-thread now installed in the ceiling. The whole system is now waiting for me to get the insulation contractor out – they’re planing to staple up a mesh and blow cellulose in the floor/ceiling space. Sometime between now and then I will weld in a couple of end-stop plates on the I-beam to keep the trolley from traveling too far toward either end. This will make sure the load is distributed among multiple trusses and that my load doesn’t crash to the floor should the trolley run off the end of the beam. Then I can slip the MDF over the all thread pieces and bolt the beam in place ready for dry wall installation. Oh, and I guess I need to paint that beam too…thinking a light grey to contrast slightly with the off-white ceiling after a primer coat. I’ll probably wait to do that just a little before it’s installed to avoid scratching it since it’s going to be moving around a bit as work is completed elsewhere in the garage (it’s a little on the heavy side).