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Post by toomanytoys on Jan 19, 2016 13:03:09 GMT -5
Guys, I'm ordering the Menards clamps online to make sure they are the same dimensions, $24.06 including processing, shipping and tax for 2. A few decades back a case of beer would get me anything done in the experimental machine shop at our tech center, castings too. The machine shop I'm thinking of I've mentioned here before, www.emachineshop.com
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Post by sundog on Jan 19, 2016 15:02:57 GMT -5
The pair of Menards Tool Shop clamps I have is better than ten years old. I will get them measured up and see if the dimensions are the same as your new clamps. I'm curious to see if they have changed over time.
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Post by Red on Jan 19, 2016 17:00:10 GMT -5
Agreed. From Red's failure they appear to be a steel, thin top plate held in place to a zinc or aluminum casting by two small diameter screws. My vision was a foot milled out of steel or aluminum that slipped over the bar. The block material is cheap, it's the setup and milling that's the expense. The top slots to fit into track are easy but ideally should have filleted corners for strength if aluminum, which will require a custom mill bit. Going over the bar the foot could be end milled out to radius match the bar and have a close fit as the expensive option. A cheaper alternative would be to plow out a groove to fit over the bar and just use the end fitment and through screw to keep the foot from rocking under clamping pressure. If this option is done you could machine out bar stock 24-36" in length and cut off the needed segments which would be less expensive. But two bar holes could utilize two fasteners for that stability. Actually the failure mode of the Bosch foot would not be that bad of an issue if they didn't use locktite to retain the screws making it problematic in their removal. Another way would be basically use T shaped stock machined to fit the groove and have a center section removed out of the center leg to fit the bar. Then two side plates are through fastened with three screws, one in the center to attach to the rail and two on the sides to fasten the T. I'm glad to read that some of the board doesn't mind the Irwin "handgun" design for the theoretical prototype we're now discussing -- have at it and God bless. If, on the other hand, anyone is interested in using what I'm now calling the "Menard Design," to create a custom version of the Bosch FSN KZW Clamp -- one with a foot that slides into the same slots on the bottom of the Mafell guide rails -- I'd be happy to pitch in for the fabrication costs.
We were definitely going to purchase another pair of the FSN KZWs with our next imported saw order -- as a backup -- so this couldn't have come at a better time for us.
And as it was brought up in this thread, I'll add that the failure I experienced -- and it wasn't anyone else's fault -- was due to rushing a panel cut. Specifically, I placed the guide rail, the FSN KZWs and our beautiful KSS80Ec saw on the unsupported side of a trestle pony and, obviously, ended up with a pair of wounded clamps.
In my opinion, the weak link(s) in our Bosch clamps are the (2) screws that hold the Guide Rail Clip (aka, Foot) onto the Bar Bracket...and please refer to the drawing posted earlier in this thread if the terminology is confusing. Considering the possible consequences -- bent guide rail, broken Bar Bracket or worse -- I was quite pleased that the screws sheared off in this way. If, as Jack pointed out, the folks at Bosch had not used such a tough thread adhesive during factory assembly, the repair would've been fairly straight-forward...but I digress.
The important point is that, regardless of which material(s) are chosen for the prototype, future repair should be near the top of the list of design considerations...but let's keep the ideas coming, regardless.
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Post by toomanytoys on Jan 19, 2016 17:40:04 GMT -5
Brad's clamp failure in another thread was the same as were the European threads that he highlighted. Having the screws the break-a-way safety link is not bad, you just need to get the screws out!
My initial thoughts were towards a solid component, but the weight of a saw and track fall could then result in a bent track where the clamp foot rides as you stated Red. For you two guys, was there any track damage upon further inspection?
It may be more useful just to have the "T" bolt on flange machined, then it would be available for any clamp or other future use for DIY. Having a machine shop do anything gets expensive real fast.
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Post by Red on Jan 19, 2016 17:58:11 GMT -5
Brad's clamp failure in another thread was the same as were the European threads that he highlighted. Having the screws the break-a-way safety link is not bad, you just need to get the screws out! My initial thoughts were towards a solid component, but the weight of a saw and track fall could then result in a bent track where the clamp foot rides as you stated Red. For you two guys, was there any track damage upon further inspection? It may be more useful just to have the "T" bolt on flange machined, then it would be available for any clamp or other future use for DIY. Having a machine shop do anything gets expensive real fast. I don't know why, but I didn't give the bottom of the Mafell guide rail in question a really close inspection after my screw-up.
I have, on the other hand, cut several more panels with the same guide rail -- sans Bosch FSN KZW clamps -- without a hitch. This indicates that the overall guide rail wasn't distorted in any way...but your point is well taken, Jack.
Once Mister Arctic Breeze leaves the mountain, I'll take a very close look at the grooves in the bottom of said guide rail for possible damage. I'm still nursing a pretty badly pulled groin muscle (friggin' ice) -- so give me a day or two on this one and I'll get back to the board with a damage report.
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Post by Red on Jan 20, 2016 22:58:30 GMT -5
I gave the Mafell guide rail in question -- the one that our Bosch FSN KZW clamps were attached to when I accidentally broke them -- a close inspection today and, fortunately, there is no sign of any damage.
So...apparently, the folks at Bosch did a pretty good job by choosing to make the Guide Rail Clip M3 mounting screws the weak point in the clamp design. Perhaps Brad can confirm this, as well?
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Post by thedude306 on Jan 20, 2016 23:16:14 GMT -5
No rail damage for me.
Not sure the screws are a design failure point though. That seems a little to convenient. And honestly I don't think it is something that bosch engineers would come up with. They can't make all their 18V drills/drivers with the same grip. They don't have an LED or good DC on the colt... I could go on but I honestly think there's no way the screws were designed to break...
I do like (love) the clamps, I just think they failed???
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Post by toomanytoys on Jan 21, 2016 8:37:39 GMT -5
I think if they thought it was a designed failure mode they would not have put a thread locking compound on the threads so it would be so damn hard to get the broken screw out, but more of an unintended consequence. They most likely needed a steel top rail for bending strength with the thin edges, and it was more economical for a light metal casting as the base. The easiest way to marry the two would be the screws that had to fit the center section and a countersink diameter that didn't compromise the top rails strength.
But it's also plausible that there was some thought to a broken clamp that needs to be replaced is more palatable to a customer then someone having a damaged track. None of us were there so we're just brainstorm speculating.
It would be expensive to machine the entire piece as one continuous block of steel. Right now my thinking is retaining the unintended screw failure mode may be an acceptable design, and still use a steel rail to fit into the track married to an aluminum machined base, but the base length is slightly increased so through screws could be used and tensioned with nylon-insert locknuts the opposite side. This way if the screws are broken during a fall then you just replace the screws and continue on since the screw holes in the aluminum would not be threaded at all.
The screws could stay at the 3mm diameter, or possibly increased to a 4mm+ for more strength during a fall, depending on everyone's thoughts.
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Post by toomanytoys on Jan 21, 2016 10:06:52 GMT -5
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Post by Red on Jan 21, 2016 16:06:08 GMT -5
Speaking as someone who retired from an engineering career, I'm happy that the weak point in the design was the M3 screws that failed in the only two cases of clamp breakage I can draw my conclusions from. Whether it was accidental or not is irrelevant, practically speaking, because it works.
If your present thinking, Jack, is to stick with design employed by Bosch -- including the backward trigger and the M3 screws -- I'm all for it...and, once again, I'll put my money where my mouth is fingers are.
My love for the design is what inspired this particular thread, so my undamaged [expensive] Mafell guide rail is telling me to stick with the present design. However -- and please excuse the pun -- employing a pair of nuts on the ends of the M3 screws is a design enhancement that would surely speed up the repair process. Regardless, I now have everything needed to effect adhesive-based repairs on my broken pair of FSN KZWs...so I'm standing by for a consensus. Please let me know, Red
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Post by toomanytoys on Jan 22, 2016 9:29:33 GMT -5
I'm waiting for the Manards clamps to show up as well as the others that I highlighted to determine if they share a common bar size. My thinking is if going through the expense of a machine shop making a batch then it should be known if the base will fit both current owners of the imported Bosch clamps and those cheaper generic clamps found in the USA. Snow may delay these clamps getting here.
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Post by Red on Jan 22, 2016 15:22:34 GMT -5
Thanks for the update, Jack...I'll keep my eyes open for your next post.
Have a good'n down in ShelbyLand
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Post by toomanytoys on Jan 23, 2016 18:17:34 GMT -5
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Post by toomanytoys on Jan 23, 2016 18:23:07 GMT -5
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Post by toomanytoys on Jan 23, 2016 18:29:54 GMT -5
I also have two of these similar Texton units on the way for next weekend.
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