AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

Does anyone have any experience with the AndyMark 3/8-16 x 7 Hex Head Bolt used in the kit of parts drivetrain bending or breaking? I was using them to design a drivetrain, but my friend said his bent this year.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

I am pretty sure they are just a grade 5 bolts. I am are pretty sure they are what we used for our 2010 Break Away chassis axles. If so we have been pretty abusive & they have held up.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

I'm pretty sure he meant 7" and not grade 7.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

This part: http://www.andymark.com/product-p/am-1055.htm

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

We have bent the KOP bolts in the KOP long configuration before [8inch wheels, Logomotion lots hard driving]. After we realized this we got some Grade 8 bolts and didn't have any problems.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

Do you have any grade 8 bolts you'd suggest using?

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

Grade 8 is a rating, not a brand. So if you find anything marked grade 8, you're fine.

Home Depot might have them, unsure. Any industrial supplier should

Socket Head bolts aren't grade 8, but are similarly strong.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

Quick check of Mcmaster shows part #91257A650 is $12.13 for a 5 pack of grade 8 bolts if you don't have a local industrial supplier.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

We used the kit chassis for logomotion, we bent the long bolts that hold on the wheels. That aspect of that chassis is not a very good design, if your robot is going to do things like drive into a wall with it's arm extended. The load of the robot falling back onto it's wheels will bend the axles.

Using a higher grade bolt might fix the problem, but it's still not a very good design.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

This is exactly what i needed. Thanks!

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

We use these all the time. They're really robust, in 2011 6 of them held the weight of our entire max-weighted robot for nearly a year and never complained, but they do bend. I'm pretty sure we don't have a single one of these that is completely straight.
Don't be too alarmed though, most of these bends are unnoticable to the untrained eye (maybe a degree or two).

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

We had one bend almost immediately, It was a pain to get out.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

Those bolts are good, but they will bend, our Logomotion bot bent all 6 and then 6 more in one season... and it only weighed 84 pounds.

The biggest issue, is that once they bend they are incredibly difficult to remove for replacement. Ours bent to the point where they caused our wheels to wobble and started throwing chains. We use grade 8 bolts now and have had no problems.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

That's the problem...then you get to call in a back up robot and watch the finals from the sidelines. BTDT

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

Try replacing them with socket head shoulder screws aka stripper bolts.

http://www.mcmaster.com/#shoulder-screws/=jintlq

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

To help in identifying ANSI Graded Bolts. Grade 2 will have no markings on the head other than possibly manufactures code. Grade 5 bolts will have 3 tic/line marks on the head. Grade 8 bolts will have 6 tic/line marks on the head of the bolt.

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

I suggest you go to Grade 8 Bolts. Please go to this web site: http://www.boltdepot.com/fastener-in...ade-Chart.aspx The Grade of a fastener is marked on the head. If you have no marks it is a grade #2, If 3 marks you have a grade 5, if you have 5 marks it is a grade 8. Grade 8 is a higher strength fastener. Here is an on line calulator : http://www.engineersedge.com/beam_be...m_bending2.htm
This is a simply supported beam with the load at the center. In your case the beam size is 3/8" dia. with the properties of the bolt head markings in the above web site from Bolt Depot.

My team also bent a grade #2 Bolt crossing the 4x6 bump. We replaced it with Grade #8. No problems since. It is not the Andy Mark Bolt it is the application and using the correct strength fastener for the job,

Norman Collier

Re: AndyMark 3/8-16 x 7 Hex Head Bolt bending
 

The kit frame axle bolts have always been a problem. On past teams that I mentored that used the kit frame, we always swapped out the kit bolts for a real grade 8 bolt. Beware that there is a problem with counterfeit bolts all over. Buy from a reputable supplier. Mcmaster would be one. In 2006 the drivers liked to get up on the platform and give the robot full throttle to launch the robot in the air. I tried to discourage this, but the bolts and frame took it.