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Old 06-24-2018, 05:43 PM   #1
Paumalu Mark
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Loading pin/rest tab installation?

Hi, I’m Mark. 1st post here. I’m looking for some technical guidance on the best way to go about installing a loading pin 3/4 the way up a Rob Allen shaft. This mod would be for using a RA shaft with my Pathos Sniper Roller 105. I have a drill press and flopper pin-hole drill-jig already.

What type/size of pin material would be best and how best to affix the pin to shaft? Press it in? Would going in easy 90 degrees to shaft axis be adequate, or better to figure out how to drill at an angle?

Lots of questions here; Any suggestions from those of you with experience in this department would be greatly appreciated. Thanks in advance!

Mahalo,

Mark


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Old 06-25-2018, 02:31 AM   #2
Mikel_24
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Re: Loading pin/rest tab installation?

Do you have a spare bent/discarded shaft you coud use for testing? Otherwise you risk ruining a perfectly usable shaft...

You can drill at 90º and then bend the pin a little backwards or drill at an angle. Your drilling jig has the neccesary holes for you to drill at angle? Otherwise you should file/mill a small flat at an angle so you can still centerpunch and then drill on a flat surface.

If the shaft are very hard, you could use solid carbide bits for metal. I buy them in 2mm from Aliexpress in packages of 10. They seem to be used for drilling electronic boards. They are cheap. Such as these:

https://www.aliexpress.com/item/10PC...ceBeautifyAB=0

Buy two packages at onces. Shipping is free so you can order more anytime, but waiting sucks. They are fragile and any short of lateral movement and they will snap. But they drill through hardnened steel no problem.

I use 2mm 316l Stainless TIG rod for the pins. Perfect fit for the 2mm drill bits I told you about.

My suggestion is to drill angled, countershink on the exit hole a bit, Use a short section of TIG rod for the pin, TIG tack weld and then sand, polish and check for straight. If it is a tiny tack, it shouldn't distort much.

If you drill straight at 90º, you can always cut the pin long, whack it with a hammer after welding (it should bend righ at the shaft) and cut to lenght.

I hope this helps!
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Old 06-25-2018, 06:16 AM   #3
Paumalu Mark
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Re: Loading pin/rest tab installation?

Mikel_24, thank you very much for the detailed instructions! That was exactly the info I needed.

Does it matter if I use stainless pins like you recommended with a spring steel/hardened steel shaft? Forgive my ignorance, but I’m asking if using different types of steel for the shaft and pin poses any corrosion or bonding issues at the joint?

Thanks again,

Mark


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Old 06-26-2018, 02:28 AM   #4
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Re: Loading pin/rest tab installation?

If the shaft is carbon steel (spring steel), then you can either use stainless or carbon steel pins. I don't think you are going to get as much galvanic couple issues (corrosion) between stainless and carbon. Is not like aluminum VS stainless.

Besides, chances are that if you are using carbon steel shafts, you already have the habit of washing them with fresh water and, maybe, even oiling sligthly before storing them.

You will probably bend, break or lose your shaft before it corrodes too badly!

Post pictures if/when you do it!
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Old 06-26-2018, 07:54 PM   #5
Paumalu Mark
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Re: Loading pin/rest tab installation?

Thanks again. I think the greatest challenge will be drilling at angle as my jig is setup for 90 degrees.

I will definitely post pics when I get around to this project.

Much appreciated advice!


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Old 06-28-2018, 09:34 AM   #6
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Re: Loading pin/rest tab installation?

Quote:
Originally Posted by Paumalu Mark View Post
Thanks again. I think the greatest challenge will be drilling at angle as my jig is setup for 90 degrees.
The hardest thing is getting the drillbit to start biting. That's why i told you it is required to file/mill a small flat that allows you to centerpunch and start de drillbit.

Best of luck!
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Old 06-28-2018, 06:57 PM   #7
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Re: Loading pin/rest tab installation?

You will get galvanic corrosion at the contact area. Why don't you use a loader assit instead of messing aroung with a perfect shaft?

Something like this:



Rob Allen sells it
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Old 06-29-2018, 03:36 AM   #8
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Re: Loading pin/rest tab installation?

My first question is what bands are you using? If you are using the default 17.5mm bands that came with the Sniper 105 then maybe a good idea would be to switch them out to 14mm or 14.5mm bands. They will give much better performance and are much easier to load and most likely you won't need a rest tab even if loading bands to the 360% I would recommend for a 6.75mm or 7mm shaft. Now if you still want to use the RA shafts that have no rest tab and still have problems loading, I think trying to mod the shaft is just way too difficult and absolutely not worth the effort. Much easier would be to just put a loading pin on the Sniper's ballast. Just take a wood screw which has the top smooth and without thread, choose a location to the side of your stock and screw it in there, then cut off the top of the screw. I did that many years back to my Riffe 120X and it works perfect for using shafts that don't have a rest tab.
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Old 06-29-2018, 09:07 AM   #9
Paumalu Mark
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Re: Loading pin/rest tab installation?

Spearq8,

Thanks for the input. I’ve been following your pool testing videos and advice on rubber sizing. With that, I already changed a few of my pipe guns with 7mm shafts down to 14mm bands from the stock 16mm bands.

I was going to change the Sniper R 105 kicker bands to 14mm. I did not know if 14mm bands would be ideal for the roller band. If you think so, I will give it a shot... Is 360% stretch ideal for the roller band as well???

Thanks!




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Old 06-29-2018, 10:14 AM   #10
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Re: Loading pin/rest tab installation?

To do the roller band length ... go with the minimum length you can get away without having any pre-stretch. Adding pre-stretch to the roller band will cause your shaft to shoot low. As for the booster band, you just cut it to 360% and you should be fine. The booster or classic band has no effect on your shaft flight as the wishbone will not flip the tail of the shaft. I tried setting up a booster band plus a non pre-stretch roller band ... but to be honest I couldn't really see an improvement over just a classic 2 x 14 band setup and using the booster band brings back some of the recoil the roller eliminated in the first place. So not sure if all the hassle with the roller is worth it. The roller without pre-stretch is really great for close in shots that don't need a lot of power. It almost feels like you are hunting with a silenced .22LR. You can see the first few shots in this video were all with the roller head without pre-stretch on an 82cm Pathos with roller head and ballast. In the pool it was very accurate and this carried over in hunting. A fish becomes a huge target once you have that kind of accuracy.




One thing about the Pathos roller head ... it has no bearings so there is probably some loss of efficiency to another head that has ceramic bearings (eg. manny sub). Also Pathos has some type of lubricant or grease on the rollers that should be removed before you use it. In my case my roller head completely seized after a day of hunting. I mean it felt like the rollers were epoxied on. Fortunately it was easy to fix ... I got the correct allen key and unscrewed the screws of the roller ... then tapped the roller slightly with a hammer and was able to remove the rollers. Washed with detergent and warm water and put the rollers back and they turning even better than before. Maybe the stuff they put reacted with the high salinity water I was in.
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Old 06-29-2018, 11:52 AM   #11
Paumalu Mark
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Re: Loading pin/rest tab installation?

Spearq8,

Great advice. Much appreciated. When you recommend to go with no pre-stretch, should the roller band have no tension at all at the muzzle, or a lighter tension than normal?

Also with this configuration, would it be best to run the roller band from the bottom ballast notch that is closest to the handle as opposed to the middle or forward-most notch?

Thanks for the advice on the roller wheels too. I will look into that.

Mark


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Old 06-30-2018, 06:59 PM   #12
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Re: Loading pin/rest tab installation?

I have to disagree with Spearq8 (again). This video shows a Rob Allen roller with pretension (not measured because I'm more practical than theoretical, but it does have enough to be difficult to load and to push the shaft all the way to the muzzle).
Btw, my 16 years old son is the one shooting the roller. I'm the one with the pneumatic.


https://youtu.be/BrnKyh10FX8

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Old 07-01-2018, 05:05 PM   #13
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Re: Loading pin/rest tab installation?

I am courious also about the pre tension. I have the Pathos Sniper Roller 115 and my band is at 300% and has no pre tension. I don’t think I could load it at 360%.
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Old 07-01-2018, 06:18 PM   #14
Paumalu Mark
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Re: Loading pin/rest tab installation?

Diver278,

Did you change out your roller band or is that the factory one? Which notch on the bottom are you using for your 300% stretch? Is the gun shooting well?

Thanks,

Mark


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Old 07-01-2018, 09:58 PM   #15
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Re: Loading pin/rest tab installation?

Yes I changed to 14mm small id. And measured from the last anchor close to handle and to the last shark fin close to trigger. With three wraps at 28 ft I shot a inch and a half group so it shoots good enough for me. Also we’re are you located?
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