HW80 rough transfer port

[sd5782]

I am playing with a Beeman R1, or HW80 for you guys across the ocean. Vintage about 2000 or so. The transfer port was drilled rough as a corncob to my eye with a magnifying glass. Size was perhaps 2.9mm. I drilled it to about 3.1 and still very rough looking ridges. I have read where .125 is optimal in FAC 80s. I did drill again, and got about 80% of the port looking smooth with that pass.
So, the question was wether or not a very roughly machined transfer port is a problem. I also have a leaky cylinder I do believe.

[oliver13]

While I can't say for sure, I don't have an HW80, when you look at the speed of the air going through a transfer port any roughness has to be a bad thing so I've always polished mine & radiused the compression side.

On the other had some aircraft aerofoils need a rough surface to work well, so who knows, but I'd polish it myself.

Maybe get some before & after readings to see if there's a difference?

[sd5782]

While I can't say for sure, I don't have an HW80, when you look at the speed of the air going through a transfer port any roughness has to be a bad thing so I've always polished mine & radiused the compression side.

On the other had some aircraft aerofoils need a rough surface to work well, so who knows, but I'd polish it myself.

Maybe get some before & after readings to see if there's a difference?

I thought about that also, but I didn't have the patience so I also have some loctite drying in the tube. I took this gun down perhaps 10 times last week with various seals and spacing being very careful to change only 1 thing at a time. This time I did seal the tube (hopefully) and cleaned up the port a bit both at the same time. Thanks

[Snooper601]

Use a reamer to get a better finish.

Cheers

John

[oliver13]

To polish the port I used the blunt end of a drill in a battery drill, some metal polish & some hours of my life. The chamfer I do through the compression tube with an old 6mm drill (ie. blunt) welded to a long rod & I go very carefully, then I deburr by running it backwards. I tried a new drill the first time & it tried to give me a 6mm transfer port...

If anyone has any other suggestions on the subject I would be very pleased to hear them.

[gibboj]

HI id be tempted to clean the transfer port up with some wet n dry and smooth out best possible [ air flow better wen it not disturbed] I also radiuse the comp tube side and some tunners put a very very slight radiuse on the breach side as well. your right about the transfer port size .i25 [3.2mm] so your not far off .try to get a new type hw piston seal as thay are said to be very good [you might have to size] not to sure wat you mean be a leaky comp tube as hw80 don't suffer from this problem ? , if your uping the power don't go to daft ie 21 ftlb hw80 are very sweet at about 17 - 18 ftlb in .22

[sd5782]

HI id be tempted to clean the transfer port up with some wet n dry and smooth out best possible [ air flow better wen it not disturbed] I also radiuse the comp tube side and some tunners put a very very slight radiuse on the breach side as well. your right about the transfer port size .i25 [3.2mm] so your not far off .try to get a new type hw piston seal as thay are said to be very good [you might have to size] not to sure wat you mean be a leaky comp tube as hw80 don't suffer from this problem ? , if your uping the power don't go to daft ie 21 ftlb hw80 are very sweet at about 17 - 18 ftlb in .22

About 80% or so of the TP is now smooth. To smooth the rest, I would either have to drill one size larger (.129") or try to polish out the rough spot and have an egg shaped port. I really don't want to do either just yet. I think I have read about leaky breech brazing on the 80 also, but perhaps some of the inefficiency in this gun was the TP also. Going to let the Loctite 271 cure for a couple of days. Not after super power, but thought 17-18 should be attainable, but so far not. I have 2 styles of JM seals, and a Vacseal that I have tried. I will post back in a couple of days with any changes.

[bigtoe01]

bootlace and metal polish like autosol or PEEK to polish the TP

[oliver13]

If anyone has any tips for radiusing the compression side of the transfer port I'd be grateful. I use a 6mm drill welded to a length of welding rod in a battery drill. It just takes a second but would be very easy to go wrong, if anyone's come up with something better I'd be grateful if you would share?

[oliver13]

About 80% or so of the TP is now smooth. To smooth the rest, I would either have to drill one size larger (.129") or try to polish out the rough spot and have an egg shaped port. I really don't want to do either just yet. I think I have read about leaky breech brazing on the 80 also, but perhaps some of the inefficiency in this gun was the TP also. Going to let the Loctite 271 cure for a couple of days. Not after super power, but thought 17-18 should be attainable, but so far not. I have 2 styles of JM seals, and a Vacseal that I have tried. I will post back in a couple of days with any changes.

Using a drill of the same diameter, with the cutting end in the drill, keep pouring on the metal polish & keep it moving in & out. It's not an exact science so keep an eye on things, you should be able to pull the plug a long time before it gets keyhole shaped for instance.

A reamer would be better of course, but you would have to buy one for that exact diameter & that's probably the only time it would ever get used.

[greenwayjames]

Years ago I had a Bowket converted HW80 in .22" on my FAC. The transfer port was drilled to over 3/16". It also had one of his simple barrel locks. Power and accuracy were spot on using old Eley wasps at 850fps. Extremely quiet, apart from the pellet flight sounding like tearing calico, and very soft recoil. Regrettably it was moved on in favour of something else on my ticket. Where are you now my beloved

[evert]

If anyone has any tips for radiusing the compression side of the transfer port I'd be grateful. I use a 6mm drill welded to a length of welding rod in a battery drill. It just takes a second but would be very easy to go wrong, if anyone's come up with something better I'd be grateful if you would share?

I use tapered diamond dremel bits like these:

http://www.aliexpress.com/item/30-pc...907335053.html

Monuted in an extender made of an old piece of cleaning rod. I go VERY slowly with a battery drill.

[NickG]

Lap it, using a brass rod shaped to what you want and lapping paste.

[Black Beard]

Reamers are only available in certain sizes. Get a 1/8" hand reamer, which gives you about 3.3mm.

[sd5782]

If anyone has any tips for radiusing the compression side of the transfer port I'd be grateful. I use a 6mm drill welded to a length of welding rod in a battery drill. It just takes a second but would be very easy to go wrong, if anyone's come up with something better I'd be grateful if you would share?

I used a length of aquarium tubing taped to a piece of rod for stiffness. Put in a drill bit that was snug in the tubing, and rotated by hand. A bit wobbly but no matter as just knocking off the sharp edge. I followed this up with a dremel stone in the same tube for a bit of smoothness.
Cleaned up TP port, and .125 size still got me 16fpe, so I don't think there is much to be gained by a mirror smooth TP.

It seems as if I have read this in regards to porting 2 stroke engines also as I was doing an RD350. Biggest areas of concern were said to be sharp edges at castings.