Explain Power Stroke

[nchunterkw]

I thought I understood this but apparently I am missing something...

Micro 355, power stroke = 10", draw wt. = 280lbs
Micro 335, power stroke = 10", draw wt. = 270lbs
Micro 315, power stroke = 10", draw wt. = 260lbs

Unless the limbs are different lengths (they look the same to me) is power stroke defined differently than just how far you draw the string up the rail to cock it?

[Goober]

It's the firing stroke lenght of the cross bow that puts the power into the bolt.

[TheBig1]

It's the firing stroke lenght of the cross bow that puts the power into the bolt.

So what you're saying is that all three have the same power stroke and WOULD be shooting the same FPS if it weren't for the change in draw weight?

Chad

[nchunterkw]

It must be all in the risers. Same limbs placed at slightly different angles in the risers, and the risers set slightly differently on the rail so as to maintain a 10" power stroke.

Keith

[newbie]

Risers make the difference. Swept forward flat swept back.

[ComfyBear]

The difference is in the "shape" of the riser. "swept forward" "straight" or "swept back".

In other words although the powerstroke is "technically" the same, what differs is how much the limbs are "PRE-LOADED". The difference can be seen by removing the string, and looking at the angle of the limbs in relation to the mainframe.
The angle of the limbs might be obtuse, perpendicular, or acute in relation to the rail/mainframe, which would attribute to the difference in the draw weight.

Hope that helps.

[L. E. Carroll]

My 335 is swept back to some degree...Does that mean the 315 is more swept back? Also, can risers be swapped to create the different models if the riser is the limiting factor? Or has the end of the rail been re-designed bolt pattern wise to prevent this swap around?

Gene

[RexKay]

Comfy bear nailed it

[Coon Gravy]

So if my calculations are correct then at 20fps per 10lbs I should be a very fast person. I love science!

[nchunterkw]

The difference is in the "shape" of the riser. "swept forward" "straight" or "swept back".

In other words although the powerstroke is "technically" the same, what differs is how much the limbs are "PRE-LOADED". The difference can be seen by removing the string, and looking at the angle of the limbs in relation to the mainframe.
The angle of the limbs might be obtuse, perpendicular, or acute in relation to the rail/mainframe, which would attribute to the difference in the draw weight.

Hope that helps.

Very good explanation. When you think of the bows without the string it all becomes very clear. Since the riser angles are different, for the same brace height, some limbs are flexed more at that brace height (high pre-load = swept fwd angle) and some are flexed less (low pre-load = swept back angle).

Now, given that they re-did the 405 risers do you think the 355 riser is really swept fwd? I bet it perpendicular at most, and the 315 is just a few degrees further swept back than a 335. If you compare pics of the 355, 335, and 315 the risers are all different for sure.

Thanks!

[Normous]

I remember when Excalibur brought out the Equinox and Vortex with the forward angle riser adding a few degrees of pre-load to the limbs and adding 20 fps.

At the time I developed my own custom shims made from aluminum to duplicate the new angle from Excalibur to conduct my own testing with positive results.

I'm glad that I still have these various custom shims because I put them through some interesting testing when Excalibur releases a new model

[colouredchameleon]

I thought I understood this but apparently I am missing something...

Micro 355, power stroke = 10", draw wt. = 280lbs
Micro 335, power stroke = 10", draw wt. = 270lbs
Micro 315, power stroke = 10", draw wt. = 260lbs

Unless the limbs are different lengths (they look the same to me) is power stroke defined differently than just how far you draw the string up the rail to cock it?

The question that you need to have answered is what is the actual measured power stroke for each model.
The 335 now states it is 10" but did not always when in fact it much less than 10". unless something has changed.
So add to that my question is what is the actual measured power stroke for the Micro 315 and the micro 355.
Which may so answer your question better.

CC

[Handline]

Could it be just a misprint? I have a printed brochure that says micro 335 has 9.5" power stroke not 10" like on website. Unless Excalibur changed things up on the 335 as well.

If it's angle of limbs then wouldn't overall length be the same of the bow for all the bows? 315 and 335 are advertised as same length 355 is 1" longer.

Also if 355 does have forward angle limbs a person may be able to reproduce that with a 335 with shims liked previously mentioned.

[flightattendant100]

Could it be just a misprint? I have a printed brochure that says micro 335 has 9.5" power stroke not 10" like on website. Unless Excalibur changed things up on the 335 as well.

If it's angle of limbs then wouldn't overall length be the same of the bow for all the bows? 315 and 335 are advertised as same length 355 is 1" longer.

Also if 355 does have forward angle limbs a person may be able to reproduce that with a 335 with shims liked previously mentioned.

2015 catalog does list 335 Micro as 9.5" power stroke. Has this been changed?

[Goober]

It's the firing stroke lenght of the cross bow that puts the power into the bolt.

So what you're saying is that all three have the same power stroke and WOULD be shooting the same FPS if it weren't for the change in draw weight?

Chad

Sorry if I misinterpreted the question.
I'm new to this also lol. I'm gonna make an ass of myself and assume it's in the limbs.