Fx transfer port and prope mod.
- Thread starter spyde82
- Start date
How far the pellet probe is pushing the pellet or slug into the barrel?
The entire led pellet is in touch with the barrel steel tube or is just partial the led skirt is hanging outside in contact with the brass?
I want to design a new pin size probe and may change the probe OD because I cannot get the original oring 6.4x1.3 size in NBR90 hardness (here in Canada still anything in millimeters are exotic item), the closest I could find is the 6.0x1.5. With harder nitril rubber material the probe may rub too much or stuck.
The entire led pellet is in touch with the barrel steel tube or is just partial the led skirt is hanging outside in contact with the brass?
I want to design a new pin size probe and may change the probe OD because I cannot get the original oring 6.4x1.3 size in NBR90 hardness (here in Canada still anything in millimeters are exotic item), the closest I could find is the 6.0x1.5. With harder nitril rubber material the probe may rub too much or stuck.
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I just added 1-1,5mm from the original prope to compensate for the skirt, so i should be the same as the original one.
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This is my attempt. Not tested yet. (No time and no possibility......)
Looks like it is a lot bigger than the HUMA variant. (square 7.2mm) I've milled it with a 2mm end mill.
Would have thought that the .22 HUMA port should have been bigger, my oval port has got more surface area than the stock dual HUMA port.
I agree with Spyde82 that increasing the TP size is the easiest and cheapest way to gain power
The oval port is bigger...but only after it causes pellet issues. I suspect the HUMA port is considerably better than the stock port. I will attempt an elongated port that isn't quite so radical. Any little bit will help.
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I found that if you elongate it forward so it messures 6,3 x 5,2mm most pellets will work and it will give you some good results.
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Just fund some chronograph results from my dreamtac compact it was shooting 860fps stock and around 30-35 shots.
with the dual TP and pin prope it shoots 910fps and have 45 shots, could not be happyer with that.
thats more then 50fps increase becouse i also turned the reg down to 125bar to get more shots pr fill. 35 shots to 45 shots..
with the dual TP and pin prope it shoots 910fps and have 45 shots, could not be happyer with that.
thats more then 50fps increase becouse i also turned the reg down to 125bar to get more shots pr fill. 35 shots to 45 shots..
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Just fund some chronograph results from my dreamtac compact it was shooting 860fps stock and around 30-35 shots.
with the dual TP and pin prope it shoots 910fps and have 45fps, could not be happyer with that.
thats more then 50fps increase becouse i also turned the reg down to 125bar to get more shots pr fill. 35 shots to 45 shots..
That is awesome. It goes to show that you always want as little transfer port restriction as possible. Less restriction equals more efficiency.
This is, of course, specific to the case of regulated airgun with a plenum. An unregulated airgun, with the restriction close to the valve (very little plenum) isn't going to suffer the same efficiency losses.
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I found that if you elongate it forward so it messures 6,3 x 5,2mm most pellets will work and it will give you some good results.
Thank you for those pics. I would think you'd want the transfer port elongated toward the back as far as possible without compromising the seal. The reason being you don't want the opening of the port to ever be past the back of the pellet. Perhaps that is not an issue with how deep the Impact seats pellets.
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This is my attempt. Not tested yet. (No time and no possibility......
Looks like it is a lot bigger than the HUMA variant. (square 7.2mm) I've milled it with a 2mm end mill.
Would have thought that the .22 HUMA port should have been bigger, my oval port has got more surface area than the stock dual HUMA port.
I agree with Spyde82 that increasing the TP size is the easiest and cheapest way to gain power
The oval port is bigger...but only after it causes pellet issues. I suspect the HUMA port is considerably better than the stock port. I will attempt an elongated port that isn't quite so radical. Any little bit will help.
I have never had any issues with pellet issues whatsoever.
If you get pellet issues, you likely went too wide on the port. That's why you should only lengthen the port, and leave the width as is.
Regarding the probe, deburr it meticulously in and out, front to back, to prevent o-ring damage.
This is my latest try on my 22cal port, I recessed the 7mm hole as far as I could.
TP size is 5mmx7.2mm
I've reached 103 joules (76ft/lbs) in 22cal, so I suppose it is doing all right
Spyde82 did right hogging it out, otherwise the gains would have been far less.
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When making a turn you always want a radius. In a tube the largest part of the flow will be on the short side radius and so the greatest gains in flow will come from there. The smoother you make the turn the greater the airflow. You want to be as close to laminar flow as possible even though you'll never achieve it.
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This is my attempt. Not tested yet. (No time and no possibility......
Looks like it is a lot bigger than the HUMA variant. (square 7.2mm) I've milled it with a 2mm end mill.
Would have thought that the .22 HUMA port should have been bigger, my oval port has got more surface area than the stock dual HUMA port.
I agree with Spyde82 that increasing the TP size is the easiest and cheapest way to gain power
The oval port is bigger...but only after it causes pellet issues. I suspect the HUMA port is considerably better than the stock port. I will attempt an elongated port that isn't quite so radical. Any little bit will help.
I have never had any issues with pellet issues whatsoever.
If you get pellet issues, you likely went too wide on the port. That's why you should only lengthen the port, and leave the width as is.
Regarding the probe, deburr it meticulously in and out, front to back, to prevent o-ring damage.
This is my latest try on my 22cal port, I recessed the 7mm hole as far as I could.
TP size is 5mmx7.2mm
I've reached 103 joules (76ft/lbs) in 22cal, so I suppose it is doing all right
Spyde82 did right hogging it out, otherwise the gains would have been far less.
You are right, i was just worryed that if i made it bigger it would not work.
i have only had troubles with some smaller slugs, but i am sure i could have got it to work with some more adjusting
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You are absolutely right but by removeing Air restriktions you Will get better flow, i would think
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You are absolutely right but by removeing Air restriktions you Will get better flow, i would think
This is my point... the view is exaggerated for clarity.
If the narrowest point in both ports is the same the one on the right will have the greatest flow.
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Ack! My tool tip bounced out when elongating the probe window and I scored the outside. Can't feel it but probably blowing air back now. Best place to buy new probe?
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It is a few grooves. Nothing raised so I just left it for now.
Dealing with another reg issue. Probably need new seals for the reg. Slow leak that is sometimes a fast leak. Suddenly the reg wasn't working at all. Reg'd pressure was the same as the bottle pressure. JSB King Heavies were smoking at 200 bar!!...1040 fps. I turned down reg one full turn...from what used to be 160 bar (when it was working) to 130 bar...and refilled and it is working...for now.
Will run it across the chrony again today to see where the porting got me.
BTW, this Impact is already outfitted with an ER power plenum.
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Interesting info. Now that I have a lathe, I really need to make one of those pin probes. I only shoot slugs, so it should work well.
As for the transfer port, it would be nice if these were available blank, so you could custom machine your own opening. I just sent Huma a message to see if that's something they would consider.
I'm also trying to decide if there would be any harm to having an extra hole. For example, you could start with the stock FX part, turned it 180 degrees, then made a new notch, and cut the new port. That would leave the stock port on the opposite side, but the o-rings on either end should prevent that from being a problem.
Rusty
As for the transfer port, it would be nice if these were available blank, so you could custom machine your own opening. I just sent Huma a message to see if that's something they would consider.
I'm also trying to decide if there would be any harm to having an extra hole. For example, you could start with the stock FX part, turned it 180 degrees, then made a new notch, and cut the new port. That would leave the stock port on the opposite side, but the o-rings on either end should prevent that from being a problem.
Rusty
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Why yes, exactly like that
Thanks for the link. I guess I need to spend more time watching youtube. BTW, Huma replied already and said they had not considered offering the transfer ports without a hole, but they would consider it. I don't remember what these cost direct from FX, but I'm sure it's cheaper if you don't mind making a new hole on the opposite side.
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