Clamps for downtube???
- Thread starter jlustig83
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spinningmagnets
100 TW
Get round tube clamps of a style that you like, that are big enough to get around your odd-cross-section bike tube. for the gap in-between, perhaps consider using an unlubricated condom filled with JB-Weld or Devcon.
Put everything in the place you want it to stay, and clamp it down 95% while the filler hardens. After its fully cured, you can cut away the condom and file the filler to shape. Its slightly easier to cut, drill, and file than aluminum.
Put everything in the place you want it to stay, and clamp it down 95% while the filler hardens. After its fully cured, you can cut away the condom and file the filler to shape. Its slightly easier to cut, drill, and file than aluminum.
AussieJester
1 TW
Personally i would be looking into drilling a few holes in the frame then fitting alumnium threaded inserts too which you can bolt mounts or the box directly to. Would look very clean and really not decrease the frames strength greatly if at all IMO... dependent of course, where on the frame you chose to drill. Couple of small 5mm size inserts on the down tube left and right of center dead middle is where i would be looking at fitting them...if you sell the bike frame in future as a pedal only bike these inserts could then be used for a water bottle perhaps...either way they don't stand out greatly.IMO next to cnced ali brackets custom made to fit the frame, threaded rivets would be the cleanest way of approaching it...
Best of luck which ever way you go...
Kim
Best of luck which ever way you go...
Kim
spinningmagnets
100 TW
I've got plenty of steel nutserts if you want a couple (I think they're M6 thread)
Hmm, I don't quite "get it", how exactly do they fit the drilled hole? Any pictures or guide for using them? I'm a mechanical/fabrication newbie but this looks promising, I'm also tinkering with a battery box that needs to attach to the frame somehow.AussieJester said:
bobc
10 kW
The top bit collapses & it holds itself in place like a pop rivet. The thread is used to set it. You can buy a special tool to set 'em or use a setscrew & 3 or 4 spanners...
I've used these on my locost car & any load or vibration & they come loose or need replacing with depressing regularity. I am usingthe aluminium ones though.
I'd still be a little wary of using them to support a heavy battery on a hardtail bike....
I've used these on my locost car & any load or vibration & they come loose or need replacing with depressing regularity. I am usingthe aluminium ones though.
I'd still be a little wary of using them to support a heavy battery on a hardtail bike....
Whiplash
1 MW
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- May 10, 2010
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I think the trick with these is they have to be held tight against the part you are holding on the bike. They require a good amount of torque on the bolt to keep them held in place. Also any jiggling and they will work themselves loose, so if you use them make sure to design it so the battery is very secure and not "jiggling" or they will work loose in their holes.
Jeremy Harris
100 MW
I've used heaps of these on two kit cars and never had one fail, but I have stripped the threads on the alloy ones a few times. I've found that, like pop rivets, they need to be fitted into a pretty precisely drilled hole (best if they are a tight push fit to get in) and squeezed with the proper Rivnut tool. I have set a few with the "screw, washer, nut and two spanners" method but they never seem to crush in the right place, they often seem to start expanding at the end, rather than behind the sheet, for some reason.
The best investment I made was to buy a set of mandrels that fit a pop rivet gun. Used with my pneumatic gun these make pulling even 8mm Rivnuts a pleasure. You can get non-metric ones in the UK, here: http://www.lasaero.com/site/products/article?id=T02UY0WNP
As for reliability, all I can say is that aeroplanes tend to be full of the things, so properly used they are fine. They are approved by the US Air Force and US NAvy and carry US aviation approval part numbers, at least the decent quality ones do. If you see any with a part number starting NAS it means it's approved for aircraft use. Next time you fly, take a look at all the screws on the aircraft skin holding on panels etc. You'll find that the majority of them are screwed into Rivnuts.
For those of you in the US who want quality non-metric Rivnuts, see here: http://www.aircraftspruce.com/catalog/hapages/rivnuts.php If you want a cheap and very good Rivnut setting tool, then this one does a great job: http://www.aircraftspruce.com/catalog/topages/rivetnuttool.php
Jeremy
The best investment I made was to buy a set of mandrels that fit a pop rivet gun. Used with my pneumatic gun these make pulling even 8mm Rivnuts a pleasure. You can get non-metric ones in the UK, here: http://www.lasaero.com/site/products/article?id=T02UY0WNP
As for reliability, all I can say is that aeroplanes tend to be full of the things, so properly used they are fine. They are approved by the US Air Force and US NAvy and carry US aviation approval part numbers, at least the decent quality ones do. If you see any with a part number starting NAS it means it's approved for aircraft use. Next time you fly, take a look at all the screws on the aircraft skin holding on panels etc. You'll find that the majority of them are screwed into Rivnuts.
For those of you in the US who want quality non-metric Rivnuts, see here: http://www.aircraftspruce.com/catalog/hapages/rivnuts.php If you want a cheap and very good Rivnut setting tool, then this one does a great job: http://www.aircraftspruce.com/catalog/topages/rivetnuttool.php
Jeremy
spinningmagnets
100 TW
Here are two un-collapsed steel M6 nutserts, and one that was collapsed using the wrench-and-vice method Jeremy described. If you put a smear of JB/Devcon on the nutsert just before inserting it into the hole and collapsing it, it will not be loose, even if the collapsing wasn't perfect. To insert them into a hole in a tube (without access to the other side of the hole) you would definitely need the proper tool.
Hillhater
100 TW
Be careful with using the "nutserts" .
They are intended for the purpose of providing a threaded location in a thin section material and are excellent when used as intended, BUT...
The application must be correctly designed and stressed. Usually these are used in "sets" of many ..like rivets.... to spread the load over a wide area of the thin material that they are inserted into.
By definition thin material is not massively strong , and if it is a load bearing member ( your bike downtube) drilling holes will weaken it to some extent and also cause "stress concentration" points at these holes. If you then go and put significant load on those mounting points you may expect problems at some stage!
Im not saying dont use them on the bike, just consider the options and chose wisely.
They are intended for the purpose of providing a threaded location in a thin section material and are excellent when used as intended, BUT...
The application must be correctly designed and stressed. Usually these are used in "sets" of many ..like rivets.... to spread the load over a wide area of the thin material that they are inserted into.
By definition thin material is not massively strong , and if it is a load bearing member ( your bike downtube) drilling holes will weaken it to some extent and also cause "stress concentration" points at these holes. If you then go and put significant load on those mounting points you may expect problems at some stage!
Im not saying dont use them on the bike, just consider the options and chose wisely.
MitchJi
10 MW
Hi,
Why not clamps?:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=22089
Strong enough to mount motors:
If used correctly:
Why not clamps?:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=22089
veloman said:I'm doing some research on the best type of clamp to use to attach my motor to the downtube of the bike frame. It's not a pure round tube, slightly oval.
T-bolt clamp
My brother had one of these in the garage and I tested it out. After tightening it down all the way, this thing is ROCK SOLID. I was afraid it might damage the frame since I can imagine it's exerting a ton of force on the aluminum, but it's a cheap Schwinn alum frame (should be quite thick).
I don't have the capabilities to build my own custom mounts, so I think these may be the next best choice.
On the plus side, they will allow adjustment for chain tensioning, and add essentially no weight. Compared to many other clamps, this style seems to have the most even contact, and therefore the best strength and least likely to harm the frame.
Strong enough to mount motors:
recumpence said:
If used correctly:
boostjuice said:Yes they work awesome on oval tubes!!
However, for oval tubes, omit using the shim that fits near the fastener. They don't conform nearly as well to non-round tubes and so will likely damage your frame.
MitchJi
10 MW
Hi,
Take your pick
:
http://www.google.com/search?q=t-cl...l=&oq=&pbx=1&bav=on.1,or.&fp=909004fa5f4cbdb2
jlustig83 said:
Take your pick
:http://www.google.com/search?q=t-cl...l=&oq=&pbx=1&bav=on.1,or.&fp=909004fa5f4cbdb2
I am currently using nutserts into a thin-wall aluminum tube and I can echo the suggestion regarding a correctly drilled hole. If the hole is a hair too big, they torque out quite easily. I find that the hole is the right size when I have to hold the tool dead straight and tap it lightly with a hammer to get it seated.
These are blind holes I'm doing, and I use the bolt and nut method to draw them tight. It has worked quite well so far. My only failure was due to a hole that was drilled slightly oversized. And one time when I dropped the nutsert down inside the seat tube. Oops.
Kim, do you suggest 5deg off dead center for access of tools? That one sort of confused me.
I am using aluminum nutserts because that is what I can get without a special order at the local fastener house.
I looked into those fancy bolting clamps, and here in Toronto, they are called "heavy duty hose clamps" at Brafasco a local fastener supplier and if I was mounting a motor, it is definitely the way I would go. BTW, kudos on that crazy epoxy and condom idea, now THAT's thinking outside the box!
Katou
These are blind holes I'm doing, and I use the bolt and nut method to draw them tight. It has worked quite well so far. My only failure was due to a hole that was drilled slightly oversized. And one time when I dropped the nutsert down inside the seat tube. Oops.
Kim, do you suggest 5deg off dead center for access of tools? That one sort of confused me.
I am using aluminum nutserts because that is what I can get without a special order at the local fastener house.
I looked into those fancy bolting clamps, and here in Toronto, they are called "heavy duty hose clamps" at Brafasco a local fastener supplier and if I was mounting a motor, it is definitely the way I would go. BTW, kudos on that crazy epoxy and condom idea, now THAT's thinking outside the box!
Katou
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