Kinda surprised at Excalibur

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lituani
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Kinda surprised at Excalibur

Post by lituani » Tue Mar 30, 2021 7:20 am

Excalibur engineers fantastic products, but they don't provide specifications for assembly.

Finally got my Matrix 355 in mail yesterday. Limb detached from riser, so need to secure the two 5/16" cap screws. All of the instruction manual's I've pulled up online only state "Tighten screws". WHAT IS THE TORQUE SPEC?

Anybody know?

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janesy
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Re: Kinda surprised at Excalibur

Post by janesy » Tue Mar 30, 2021 9:16 am

lituani wrote:
Tue Mar 30, 2021 7:20 am
Excalibur engineers fantastic products, but they don't provide specifications for assembly.

Finally got my Matrix 355 in mail yesterday. Limb detached from riser, so need to secure the two 5/16" cap screws. All of the instruction manual's I've pulled up online only state "Tighten screws". WHAT IS THE TORQUE SPEC?

Anybody know?
There are no advertised torque specs available to the public. Tighten them past hand tight, and then cinch them down another 1/4 turn. They go on fairly tight.

Little bit of blue locktite applied properly will help
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Re: Kinda surprised at Excalibur

Post by Boo » Tue Mar 30, 2021 9:34 am

You think you had issues about the lack of torque specs? Try being an auto mechanic who rebuilds transmissions, differentials, engines and repairs circuit boards! Not only that be we are going from steel into aluminum! Add to that there are atleast 3 differrnt types of aluminum that have threads in an Excalibur! :wtf: Well, I had an epiphany! Guess what? The precise torque is not important! I felt like a nerd because of what I knew professionally and what I expected out of Excalibur. There are no critical fasteners. Tighten things well enough that they don't come lose. The metal used is very good quality and thickness is appropriate. Keep lubricants off the threads and don't run a tap on any threads unless they are damaged.
I use a T handle and I can give you 3 non technical specs. Limb bols and riser to mainframe bolts as tight as I can get them with one hand and the scope base the shaft on the T handle twists 90 to 100 degrees. Make sure allens tools are fully seated before tightening. Everything with the exception of the 4 largest fasteners seem to need magnetic bits beaten in to get full engagement.
If I remember, the next time I take a bow apart, I'll use a torque wrench and jot down some numbers.
BTW, the reason for not running a tap is that there is a large dimensional difference between taps and Excalibur does not use a conventional tap.
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lituani
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Re: Kinda surprised at Excalibur

Post by lituani » Tue Mar 30, 2021 10:50 am

Boo wrote:
Tue Mar 30, 2021 9:34 am
You think you had issues about the lack of torque specs? Try being an auto mechanic who rebuilds transmissions, differentials, engines and repairs circuit boards! Not only that be we are going from steel into aluminum! Add to that there are atleast 3 differrnt types of aluminum that have threads in an Excalibur! :wtf: Well, I had an epiphany! Guess what? The precise torque is not important! I felt like a nerd because of what I knew professionally and what I expected out of Excalibur. There are no critical fasteners. Tighten things well enough that they don't come lose. The metal used is very good quality and thickness is appropriate. Keep lubricants off the threads and don't run a tap on any threads unless they are damaged.
I use a T handle and I can give you 3 non technical specs. Limb bols and riser to mainframe bolts as tight as I can get them with one hand and the scope base the shaft on the T handle twists 90 to 100 degrees. Make sure allens tools are fully seated before tightening. Everything with the exception of the 4 largest fasteners seem to need magnetic bits beaten in to get full engagement.
If I remember, the next time I take a bow apart, I'll use a torque wrench and jot down some numbers.
BTW, the reason for not running a tap is that there is a large dimensional difference between taps and Excalibur does not use a conventional tap.
Exactly - hey Excalibur, whiskey tango foxtrot!!! :thumbdown:

As an automotive engineer, I feel your pain Boo (and probably have contributed to some of your banged knuckles). Without going into dissertation, they are all important (not necessarily critical) fasteners, else they wouldn't be there. Properly design joints have minimum 4 full threads engagement for similar materials; those two limb bolt/riser screws have at least 5 threads engaged, so that box is checked.

Torque specs are generally ft-lbs or Nm. Lacking that, it's "one oomph" or "two oomph". I generally avoid T-handles and use 90-degree torque tools for better feel/control. Given these steel fasteners are going into aluminum, two oomph could lead to stripouts. Guess it's a strong "one oomph".

So much for fasteners, now on to tools. In one instruction manual, they gave you a choice: 3/16" or 7/32" hex. Truly a WTF moment!

Hey Excalibur - opportunity for improvement.

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Re: Kinda surprised at Excalibur

Post by Boo » Tue Mar 30, 2021 1:31 pm

lituani wrote:
Tue Mar 30, 2021 10:50 am
Boo wrote:
Tue Mar 30, 2021 9:34 am
You think you had issues about the lack of torque specs? Try being an auto mechanic who rebuilds transmissions, differentials, engines and repairs circuit boards! Not only that be we are going from steel into aluminum! Add to that there are atleast 3 differrnt types of aluminum that have threads in an Excalibur! :wtf: Well, I had an epiphany! Guess what? The precise torque is not important! I felt like a nerd because of what I knew professionally and what I expected out of Excalibur. There are no critical fasteners. Tighten things well enough that they don't come lose. The metal used is very good quality and thickness is appropriate. Keep lubricants off the threads and don't run a tap on any threads unless they are damaged.
I use a T handle and I can give you 3 non technical specs. Limb bols and riser to mainframe bolts as tight as I can get them with one hand and the scope base the shaft on the T handle twists 90 to 100 degrees. Make sure allens tools are fully seated before tightening. Everything with the exception of the 4 largest fasteners seem to need magnetic bits beaten in to get full engagement.
If I remember, the next time I take a bow apart, I'll use a torque wrench and jot down some numbers.
BTW, the reason for not running a tap is that there is a large dimensional difference between taps and Excalibur does not use a conventional tap.
Exactly - hey Excalibur, whiskey tango foxtrot!!! :thumbdown:

As an automotive engineer, I feel your pain Boo (and probably have contributed to some of your banged knuckles). Without going into dissertation, they are all important (not necessarily critical) fasteners, else they wouldn't be there. Properly design joints have minimum 4 full threads engagement for similar materials; those two limb bolt/riser screws have at least 5 threads engaged, so that box is checked.

Torque specs are generally ft-lbs or Nm. Lacking that, it's "one oomph" or "two oomph". I generally avoid T-handles and use 90-degree torque tools for better feel/control. Given these steel fasteners are going into aluminum, two oomph could lead to stripouts. Guess it's a strong "one oomph".

So much for fasteners, now on to tools. In one instruction manual, they gave you a choice: 3/16" or 7/32" hex. Truly a WTF moment!

Hey Excalibur - opportunity for improvement.
Ok, you are an engineer. Why is it that there are no SAE torque specs for aluminum. I can mention one and I'm sure there's many, there are too many variables. The riser, mainframe and trigger unit are all different alloys. My question to you is not rhetorical. I've often wondered.
In my world, thread engagement is the diameter of the fastener plus 25%.
In the end, how many guys own a torque wrench let alone use one on the bow? I certainly don't! I've turn a bazillion bolts by hand and professionally, we mechanics aren't paid for the time to look up every spec and get out the torque wrenches and use them with the exception of critical parts. On an Excalibur, there are no such critical parts.
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Re: Kinda surprised at Excalibur

Post by lituani » Tue Mar 30, 2021 2:15 pm

Boo wrote:
Tue Mar 30, 2021 1:31 pm
Ok, you are an engineer. Why is it that there are no SAE torque specs for aluminum. I can mention one and I'm sure there's many, there are too many variables. The riser, mainframe and trigger unit are all different alloys. My question to you is not rhetorical. I've often wondered.
In my world, thread engagement is the diameter of the fastener plus 25%.
In the end, how many guys own a torque wrench let alone use one on the bow? I certainly don't! I've turn a bazillion bolts by hand and professionally, we mechanics aren't paid for the time to look up every spec and get out the torque wrenches and use them with the exception of critical parts. On an Excalibur, there are no such critical parts.
Yep, unapologetically engineer by birth.

Actually there are plenty of examples of torque specs for aluminum in the car biz. For example, you'll find them for virtually every powertrain fastener (engine, transmission, PTU and RDU) in shop manuals or online. Every dealership mechanic follows them; unsure about independent shops. Agree not every fastener is a critical part, but there are no superfluous fasteners. Everything's gotta be guttentite (a little german lingo).

All the different aluminum alloys used by Excalibur are result of cost/benefit equation:
==>Rail is most cost effective (and typically strongest) being an extruded alloy.
==>Riser, made from a "chunk" of aluminum starts out either as solid block with everything machined away, or die-cast for near net finished shape (alot less machining required). Strength requirements determine whether alloy alone or subsequent heat treating achieve desired properties.
==>Trigger group has alot of small parts, several of which are high surface stress wear components and will typically be steel (although using aluminum can reduce weight in non-critical areas). Alot of attention to detail required if steel & aluminum are mixed within the assembly with mating surfaces.
But, Excalibur uses aluminum mostly to minimize weight. Their design doesn't require much concern for cathode/anode reaction between dissimilar materials.

Your "diameter plus 25%" is good rule of thumb. But notice how all hex nuts are 4-5 threads: generally anything beyond that is wasted metal except in high torque joints (where premium materials can provide same benefit as additional thread count). This subject is a whole other dissertation based on application.

Don't know about bow shooters, but firearm shooters pay attention to torque specs (especially scope rings). Guess I just carried that torque discipline over to crossbows. Again, unapologetically (where's the slide rule emoji?).

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Re: Kinda surprised at Excalibur

Post by Hi5 » Tue Mar 30, 2021 2:38 pm

..
Last edited by Hi5 on Tue Mar 30, 2021 2:46 pm, edited 1 time in total.
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Re: Kinda surprised at Excalibur

Post by janesy » Tue Mar 30, 2021 2:46 pm

Hi5 wrote:
Tue Mar 30, 2021 2:38 pm
Scope rings?

The only ones that comes to mind on a firearm would be screws that secure the action into the stock. I doubt that there is any more critical area where pressure should be exact and consistent. There is no data from any manufacturers that I know.
17in-lb for scope rings at the base and the ring.

But the only reason I even use a torque driver, is because absolutely nobody else does that I know. So when I tune their bow or rifle each year, it leaves my house set up as best I possibly could. That way if they strip the threads later, it's on them not me.

Most people I would say have no idea there even is a torque rating :lol:
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Re: Kinda surprised at Excalibur

Post by Boo » Tue Mar 30, 2021 2:53 pm

lituani wrote:
Tue Mar 30, 2021 2:15 pm
Boo wrote:
Tue Mar 30, 2021 1:31 pm
Ok, you are an engineer. Why is it that there are no SAE torque specs for aluminum. I can mention one and I'm sure there's many, there are too many variables. The riser, mainframe and trigger unit are all different alloys. My question to you is not rhetorical. I've often wondered.
In my world, thread engagement is the diameter of the fastener plus 25%.
In the end, how many guys own a torque wrench let alone use one on the bow? I certainly don't! I've turn a bazillion bolts by hand and professionally, we mechanics aren't paid for the time to look up every spec and get out the torque wrenches and use them with the exception of critical parts. On an Excalibur, there are no such critical parts.
Yep, unapologetically engineer by birth.

Actually there are plenty of examples of torque specs for aluminum in the car biz. For example, you'll find them for virtually every powertrain fastener (engine, transmission, PTU and RDU) in shop manuals or online. Every dealership mechanic follows them; unsure about independent shops. Agree not every fastener is a critical part, but there are no superfluous fasteners. Everything's gotta be guttentite (a little german lingo).

All the different aluminum alloys used by Excalibur are result of cost/benefit equation:
==>Rail is most cost effective (and typically strongest) being an extruded alloy.
==>Riser, made from a "chunk" of aluminum starts out either as solid block with everything machined away, or die-cast for near net finished shape (alot less machining required). Strength requirements determine whether alloy alone or subsequent heat treating achieve desired properties.
==>Trigger group has alot of small parts, several of which are high surface stress wear components and will typically be steel (although using aluminum can reduce weight in non-critical areas). Alot of attention to detail required if steel & aluminum are mixed within the assembly with mating surfaces.
But, Excalibur uses aluminum mostly to minimize weight. Their design doesn't require much concern for cathode/anode reaction between dissimilar materials.

Your "diameter plus 25%" is good rule of thumb. But notice how all hex nuts are 4-5 threads: generally anything beyond that is wasted metal except in high torque joints (where premium materials can provide same benefit as additional thread count). This subject is a whole other dissertation based on application.

Don't know about bow shooters, but firearm shooters pay attention to torque specs (especially scope rings). Guess I just carried that torque discipline over to crossbows. Again, unapologetically (where's the slide rule emoji?).
I should have been more clear. SAE puts out info for a chart that gives you a torque range for any fasteners categorizing diameter, fastener grade and pitch. But they don't apply to aluminum.
I had a hard time believing it but the risers are an extrusion prior to some machining.
BTW, my daughter holds a PHD in Industry Engineering. From the day she could talk, we figured she was going to be a cop or an Engineer :eusa-dance: Always, there's only one way, that's the right way. I guess it didn't help that half her blood is Deutsch! :lol: :lol: :lol:
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Re: Kinda surprised at Excalibur

Post by flinthead » Tue Mar 30, 2021 3:56 pm

My method has always been to crank it down until it strips... then I back it off half a turn... :eh:
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Re: Kinda surprised at Excalibur

Post by Hillcountry » Tue Mar 30, 2021 5:42 pm

Righty-tighty, lefty-loosey...loctite blue is your friend!
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Re: Kinda surprised at Excalibur

Post by Doe Master » Tue Mar 30, 2021 7:48 pm

As I have found most people have no clue how to operate a torque wrench . One click don`t wait for the second !!
We use roll form taps for the aluminum .
There was a time when we did say a recommended setting . But that was before people started to use red loc-tite . :shock:
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Re: Kinda surprised at Excalibur

Post by xcaliber » Tue Mar 30, 2021 8:43 pm

Hillcountry wrote:
Tue Mar 30, 2021 5:42 pm
Righty-tighty, lefty-loosey...loctite blue is your friend!
Yep! Ifin it's a sumbitch to get apart, twas tight! :lol: :lol:
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Re: Kinda surprised at Excalibur

Post by wheelie » Tue Mar 30, 2021 9:45 pm

No torque values on furnaces or fireplaces either! I have to make a call. :thumbup:

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Re: Kinda surprised at Excalibur

Post by wheelie » Tue Mar 30, 2021 9:59 pm

:)

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