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grover posted:A few 99-cent concrete blocks do wonders for adjusting jack height, FYI. You and your mod-logic are not welcome here! This is the TOOL thread! Not the masonry thread!
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# ? Jan 1, 2011 00:35 |
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# ? May 4, 2024 16:26 |
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Rhyno posted:You and your mod-logic are not welcome here! This is the TOOL thread! Not the masonry thread!
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# ? Jan 1, 2011 00:38 |
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Isn't there a danger the cinder blocks could fracture and collapse?
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# ? Jan 1, 2011 03:08 |
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mod sassinator posted:Isn't there a danger the cinder blocks could fracture and collapse? Yes. Concrete doesn't bend or creak before failure, so it tends to be a surprise when your camaro drops on your mulleted head.
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# ? Jan 1, 2011 03:32 |
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Theres also a danger that your jack stands could fail as well. Cinderblocks take a shitton of pressure to crush though. Just keep them upright like they should be
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# ? Jan 1, 2011 04:23 |
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Brigdh posted:Theres also a danger that your jack stands could fail as well. Cinderblocks take a shitton of pressure to crush though. Just keep them upright like they should be Uhhhh the fail point of a cinder block is much higher than that of a solid steel jack stand. A brick is just some loose particulate stuck together and cooked. When I was in high school one of my football teammate's dads collapsed a lung when his dumb rear end used solid cinderblocks for jackstands.
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# ? Jan 1, 2011 05:48 |
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Please, please never use cinderblocks to hold anything in the air that may have any body part under it. Ever.
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# ? Jan 1, 2011 06:34 |
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I'd honestly be more worried about this: http://www.ezcarlift.com/ basically an oversized scissors jack with no mechanical stops on little plastic caps using a couple of cinderbocks with the proper caps to spread the load to boost up the jack is fairly safe, all things considered.
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# ? Jan 1, 2011 07:05 |
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Lowes cuts wood for cheap, or free if the employees care very little.
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# ? Jan 1, 2011 07:20 |
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Wood can be fine, but you want big, solid lumps of it, a shape that's naturally stable, and pay attention to which way the grain's running. A stack of small pieces is still a really, really bad idea. An old railway sleeper makes a good way of raising a trolley jack another 6", but you have to make sure it can't move. One danger is that the concentrated load of the wheels can compress the wood, and if that happens unevenly, the whole thing will start to tilt over. The issue with cinder blocks and bricks is that, while they are quite strong in compression, this is based on them being part of a wall, and evenly loaded. Again, if you put something like a jack on a cinder block, or stick it under an axle, you're then putting a hefty point load onto it - it might just crush a little bit, or it might crack, or explode into a small pile of rubble. If you put a steel plate or something on it first, it might be ok, but I wouldn't bank on it. Also, the compressive strength of a brick might be as low as 3.5MPa. Steel? Hundreds of MPa. Four figures for some grades. The point is, a jack, an axle stand, a hoist or whatever is a piece of lifting equipment. It is designed, tested and rated to lift and/or support a given load, usually with a safety factor of 4:1 or higher. Do not use anything else unless you know exactly what you're doing, and "I've been doing this for years" or "Someone on the internet said" does not cut it. If you find yourself not having enough height on your trolley jack or stands, you should probably just get a bigger one. I use a long-chassis 2-tonne trolley jack, which will lift from 5.5" to 32" - my cheapo basic one might drop slightly lower (about 5"), but the 15" max height was a joke on some of my cars - wouldn't even touch the jacking point in the first place.
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# ? Jan 1, 2011 14:53 |
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mod sassinator posted:Isn't there a danger the cinder blocks could fracture and collapse? Hollow blocks are horribly unsafe for this, especially when laid on their side as people are apt to do, I don't think there's any question of that. Fortunately, solid concrete blocks are readily available and are much stronger for this. I use solid 4" cap blocks when I need a little extra lift height. grover fucked around with this message at 15:46 on Jan 1, 2011 |
# ? Jan 1, 2011 15:38 |
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As an update, I just got back from Harbor Freight. For some reason, they DID take 25% off the sale price of the jack stands (sale price was $44, marked down from $55), so they ended up $33 per pair, which is pretty good. I'm psyched to have decent clearance next time I'm rolling around under my vehicles As a related note, jack stands easily act as point loads, and it is a bad idea to place them on an unconstrained concrete surface (like a block not contained in a form), holes or no holes. Stacking items to support a vehicle is bad practice, in general, anyway. CatBus fucked around with this message at 17:57 on Jan 1, 2011 |
# ? Jan 1, 2011 17:53 |
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Brigdh posted:I'd honestly be more worried about this: For the price you could get a real lift, used, shops are unloading lifts like crazy. But the main issue is having enough space and making sure your concrete is thick enough. Aeka 2.0 fucked around with this message at 19:37 on Jan 1, 2011 |
# ? Jan 1, 2011 19:34 |
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That's provided you get a good lift that isn't overrated http://www.youtube.com/watch?v=XLUjq6ijvVc
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# ? Jan 1, 2011 22:49 |
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Aeka 2.0 posted:For the price you could get a real lift, used, shops are unloading lifts like crazy. I would love to have a real lift, unfortunately I rent a 1 car garage, and the concrete doesn't look that great. hydrolic scissors lifts don't provide enough access, and the thing I pointed out doesn't have any kind of locking mechanism that I can discern. I need to buy a house with a decent garage or something.
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# ? Jan 2, 2011 00:58 |
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When ever Ive used cinder blocks in the past I would put 2-3 pieces of dunnage between the block and car. Dunnage is the wood that comes strapped to the underside of bundles of bulk wood. You can get them free at Lowe's or Home Depot if you ask the lumber people nicely. I still keep the jack there as backup along with more than one backup incase stuff fails. Such as if you take the wheel off, put it under the car. Something to keep it from dropping all the way to the ground. I have a few old tires I use for this purpose too, lay the wheel/tire down, throw old tire ontop. Ive fully lowered a crapbox civic on a stack like that and it was solid. I will say I never went under it.
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# ? Jan 2, 2011 02:45 |
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Brigdh posted:the thing I pointed out doesn't have any kind of locking mechanism that I can discern. It's a screw jack, it IS the locking mechanism.
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# ? Jan 2, 2011 03:35 |
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oxbrain posted:It's a screw jack, it IS the locking mechanism. My engineering professors would have disagreed.
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# ? Jan 2, 2011 04:14 |
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What is a good tool/product for getting baked on oil off an aluminum engine block in tight spaces?
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# ? Jan 2, 2011 06:37 |
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Brigdh posted:What is a good tool/product for getting baked on oil off an aluminum engine block in tight spaces? Easy Off and a toothbrush? Make sure to flush thoroughly as it can gently caress with aluminium if it sits too long.
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# ? Jan 2, 2011 06:50 |
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There's also an aluminum safe version of simple green that might work well: http://www.simplegreen.com/products_extreme_motor.php
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# ? Jan 2, 2011 09:19 |
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Jared592 posted:People Plasti-dipping all kinds of stuff these days: This is getting done to my track car once it gets warm enough to paint outside.
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# ? Jan 2, 2011 17:55 |
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Brigdh posted:My engineering professors would have disagreed. Did you drop out before friction 101?
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# ? Jan 2, 2011 22:34 |
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oxbrain posted:Did you drop out before friction 101? Friction is easy enough to reduce that I'm not about to trust my life to something that relies on it. Not to mention the possibility of the screw mechanism itself failing catastrophically.
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# ? Jan 2, 2011 23:04 |
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I'm inclined to agree. There's a big difference between getting under something with only a jack supporting it, and something with stands / some equivalent supporting it. It really is just an overgrown scissor jack. While I really like the idea and the usefulness of it, I wouldn't get under a car held up by a scissor jack, and I wouldn't get under that either...and using it to put your car on stands is overkill compared to a regular hydraulic jack.
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# ? Jan 2, 2011 23:36 |
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I thought something like that would be cool for changing wheels and brakes at the track, but for $1600 hell no. And the paddock can be grass and gravel too, and I'll bet it's useless in that.
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# ? Jan 3, 2011 00:08 |
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A screw jack will not suddenly rotate and drop. There is far too much friction, and no lubricant known to man will change that. The only way it's going to suddenly drop is if you strip off every last bit of threading, which would require far more weight than it would have lifted in the first place. It's basically a big bolt and nut, and you're constantly trusting your life to those. Getting under a car on a scissors jack is dumb because it's narrow and might tip, and because scissors jacks are generally made of poo poo materials.
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# ? Jan 3, 2011 02:57 |
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Torsen differentials wouldn't work if worm/screw drive could spin itself the other way.
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# ? Jan 3, 2011 03:37 |
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Baby Hitler posted:Torsen differentials wouldn't work if worm/screw drive could spin itself the other way. while this is true, the pressure angle is what matters. Torsen diffs are setup with the pressure angle almost 90 deg off from what you'd find on a screw jack. If screws didn't self lock, screws would just fall out of everything.
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# ? Jan 3, 2011 04:53 |
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This very forum has pictures of a new (unused) GM scissor jack failing catastrophically by stripping every thread on the screw. It's a horrible design for a lift.
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# ? Jan 3, 2011 05:15 |
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While a leadscrew isn't that likely to back itself out (as Nerobo pointed out, applications where this is desired use a much higher helix angle), you do still have to worry about it stripping. And even if it's perfect when new, over time you can get wear in the components. I had an issue with clamp on a cut-off saw at one place I worked where it just wouldn't tighten down on the workpiece properly - turned out that debris had been working its way into the screw thread over time, and while the thread itself was perfectly fine (hardened steel), the block it ran in (bronze, I believe) had been worn almost completely smooth in just a few years of use. It'd screw down, but anything more than the lightest resistance would cause it to skip and back off. From the outside, you couldn't see anything wrong with it. Now, that's a fairly extreme example, and it's not likely to happen with an occasionally-used jack, but stuff like this can go wrong. And, as Skyssx pointed out, the jack might well be poo poo in the first place. Most leadscrews are ok, but if you don't look after them (grease the threads etc), you might end up dropping a car on your head. Or bring down an aircraft.
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# ? Jan 3, 2011 13:33 |
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FatCow posted:This is getting done to my track car once it gets warm enough to paint outside. Post a thread when you do please, as I think it'll encourage a lot of others to do so more than my post buried in the Tools! thread.
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# ? Jan 3, 2011 20:16 |
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Anyone ever use the harbor freight plastic welding kit? http://www.harborfreight.com/plastic-welding-kit-80-watt-iron-67102.html?utm_term=67102&tag=froogle Not car related but the plastic housing/frame inside my gas range that holds the circuit board and control panel just snapped the other day when the off button was pushed with the front face of the control panel caving in. All the boards are fine, just this frame/housing thing that's broke. I can't buy it by itself, have to buy the whole assy boards and everything for like $100. What I'm talking about is basically just like a plastic car-stereo mounting kit. Picture one of those that's broke on the top and bottom horizontal rails. (this plastic frame is hidden behind some metal a "backguard" with only the button face overlay showing, so I can ugly it up a bit with no cares) Wondering if anyone's used this and if it's any good for repairing stuff like this. Is there some kinda of glue that I could use and jig up with some c clamps that would work better? It is going to have to handle a little bit of pressure from butan-mashing. Vin BioEthanol fucked around with this message at 17:35 on Jan 5, 2011 |
# ? Jan 5, 2011 17:28 |
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I'd imagine you could probably do that with just some 2-part epoxy made for plastic. Home Depot or Lowes'll have that.
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# ? Jan 5, 2011 17:54 |
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Thanks, I don't know why I didn't think of that. Probably cause it's been years since I've used any epoxy on anything and maybe partly cause I keep seeing the plastic-welding kit in the ads and it's like a tool looking for a reason for me to buy buy buy!
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# ? Jan 5, 2011 18:09 |
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If you use epoxy just make sure you get high-quality stuff, generally speaking the longer the cure time the stronger its going to be after setting up. Avoid anything that has a "5 minute working time/20 minute cure time" or similar.
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# ? Jan 5, 2011 18:13 |
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If it's just holding a circuit board or something small you might even try super glue. It works great on plastic.
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# ? Jan 5, 2011 19:08 |
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mod sassinator posted:If it's just holding a circuit board or something small you might even try super glue. It works great on plastic. I would normally, use that poo poo on everything including myself but this also has to hold the thing in place with hungry people on the other side pushing on the membrane buttons.
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# ? Jan 5, 2011 19:59 |
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I've used the plastic welding kit. It works, but isn't very good. I've used larger ones, and they work MUCH better. For something like you are taking about, I'd use epoxy and some steel reinforcement pieces. Drill the steel, and let the epoxy flow through it, making a "rivet" out of the epoxy. We use it a lot on fishing boats to hold fluxgate compasses and autopilot rudder feedback arms. Works fine.
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# ? Jan 5, 2011 21:50 |
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# ? May 4, 2024 16:26 |
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Where do I find a spanner or monkey wrench for a 52mm nut? No one in town has anything close
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# ? Jan 6, 2011 21:56 |