Exocet to target bow conversion

[shafferm]

My Moultrie 440 pound game scale arrived so I was able to start taking measurements of poundage versus draw distance. The bow was originally an Exocet 175 with a set of Magtip limbs. I set the brace height at 1" and zeroed out the scale. I took measurements in one inch increments and got the following measurements, 0,20,30,40,50,60,65,72,80,90,100,115,125,140,150, and 170 pounds. So to get a bow down to 90 to 100 pounds of draw weight will need to trim the rail down to give between 9 and 10 inches of travel. Has anyone else performed draw distance and pull weight measurements that they would be willing to share?

[longbow joe]

Can you find a used matrix rail when you figure out the length you need?

[gerald strine]

I have not converted any bows but Danny Miller has Cut rails before and he is a Excal Warranty center.
If you wait until the busy season slows down he would be a good man for the job .
740 483 2312.

[flightattendant100]

Are you sure that the cast riser Exocet was a 175 lb. bow? I thought the cast ones were 165. But I could be wrong.

[gerald strine]

I think the carved tip are 165 lb , he stated that his was a mag tip.

[shafferm]

The carved tip Exocets were 165 pounds and the first mag tip limb versions were listed at 175 pounds. To get to the desired poundage it looks like it will require shaving off around 5 inches. I laid out what material would need trimmed down with marker. The very front sides of the stock will need a little trim as well for the riser and the rearmost riser bolt will also need to have some clearance added to the stock. Planning to make an internal spacer to use a smaller head bolt for the rear riser bolt to allow a smaller through hole in the front of the stock.





I was comparing the power stroke for the shortened rail to get to ~100 pounds draw weight and it is around 10 inches. The Apex bow uses a forward angled riser and has a power stroke of 11.8" but it is only a 90 pound draw weight. So the rail lengths and draw weights did not seem to be matching up. There were reduced power limbs that Excalibur made at one point, and I was lucky enough to win a carved tip set at Boofest a few years ago. The indication that they are reduced power is the two notches at the base of the limb. So I went to look at the Apex and looking closely at the limbs they had the same notches, which means that they are a reduced power limb with magtips. This is why the power strokes and rail lengths were not matching up with the weight scale measurements that I had taken. It also explains how the Apex has clearance from the riser. So while the Apex is a great bow by itself, it does not make a very good model to match draw weights unless you are also able to find the reduced power limbs.

[Hatchet]

Could you share a pic of the reduced power limbs? And the notched area?
Thanks
Take care
Hatchet

[shafferm]

Hatchet,

The reduced power limbs look the same as their full power versions, although the only reduced power limbs I have seen have been all black.

Here is a magtip set on the Apex


Along with a carved tip set showing the reduced power and full power limbs for comparison.


Getting back to the ApeXocet machining.

I took the rail over to the mill after rough sawing it to length and got it trammed in square and trimmed down the total length.


After a flip and resquaring I trimmed out the 3" long notch for the riser at 1.240" deep from the top of the rail.


One more flip and tramming it in and it was time to make some through holes, for the two riser through holes I used a 23/64" drill bit, they are spaced 0.5" and 2.5" for centers starting from the left side of the photo. I also drilled and tapped the #10-32 sling stud using a #21 drill bit and tap.


I then mounted the stock to the rail while still in the vise so that I could make a clearance hole in the stock for the rear riser bolt. I used a 9/16" end mill and kept it in location over the rear riser bolt hole. I picked up a new 5/16 bolt at the hardware store and a 7mm washer that I filed out a little bit to fit. Did not want to remove 1" worth of clearance for the original mounting bolt and washer.


Here is what the bottom now looks like after opening up the bottom of the stock.


I wanted to reinforce the inside of the rail since it was now over a smaller area, so I popped over to the lathe with some 7/8" round stock and turned an internal spacer. Here it is in the front position to make it easier to see. It spreads out the pressure and keeps from crushing the rail when tightening the riser bolt.


The next step was to notch the top of the stock for the riser. I used a spare piece of aluminum to get it square with the vise and used a 3D printed fixture to clamp it in the vise without risking marring up the stock along with the remnant rail piece. More to come on the fixture as it was not originally designed as a fixture, but worked great for stock holding in a vise.


I milled down 1/8" to give a bit of clearance for the riser to nestle in with the stock.


Here is the riser in it's new home with the stock.


Here is what the bottom of the bow now looks like.


Here is the bow with the machining completed. It is now right around 100 pounds and an overall length of 33 inches, so it is roughly 3 inches shorter than wide. The arrows in the photo are some 18" Diablos and come to the end of the stirrup. The trigger breaks right around 2.75 pounds. With the light draw weight it is definitely a pleasure to shoot.

[wheelie]

You will love it. I take mine to 3D shoots even. I love the reaction of people when I shoot. "Wow look at the arch." Certainly has been my go to bow for many years now. Year or two ago it was the only crossbow I kept when I was forced to sell some off. Now look for a forward riser, set of limbs and second scope and it will raise it 25lbs and not have to reline scope.

[mr meat]

Great job

[Hatchet]

Thanks for the pics Mike. I was able to confirm that our original Apex limbs are notched like that. I put a spare set of Exo limbs on it for hunting turkeys and the draw weight was over 100lbs. I had to get it up to 100lbs to be within our states minimum draw weight for hunting.

Great job on your modifications. Very professional fit and finish. Looks like it could have come from the factory like that.

I just had a rail cut at a local shop and was shocked when I saw how sloppy of a job they did. The riser wasn't centered on the rail and it was 1/16" higher than the rail. I was able to do some dremel work and hand filling and make it fit right but I have learned not all machine shops can handle this type of work.
Take care
Hatchet

[Normous]

Well done mister!

[shafferm]

Hatchet,

Sorry to hear that the machine shop that you took it to was not able to do a decent job on the modifications. Good to hear that you were able to at least get it fixed up yourself afterwards. I do this type of machining as a hobby so I am not particularly rushed on fun one off jobs like riser modifications. This bow safely made it to its new owner in Virginia.