Driiling 1720T transfer port questions

[Jaje7654]

I want to drill the transfer port for my Crosman 1720T pistol to .109"=7/64" to increase the power. I don't have access to a drill press. I have an electric hand drill, a vise, and a large selection of drill bits

Is it possible to drill the hole straight enough with a hand drill? Some say that because the transfer port is aluminum that drill bits not designed to cut aluminum will catch instead of drilling smoothly. I don't own drill bits designed to cut aluminum. If it is feasible to drill the transfer port with a hand drill, should I start with a 5/64" bit then a 3/32" and finally the 7/64"? Would it be better to just purchase a .109: TP from a seller like Hill Airguns? Thanks for any replies.

 

[Skip-in-WV]

If the TP is like the rest I've seen you can use a piece of tubing like the one for a water line in a fridge. Lowe's has it. If you like PM me with your address and I'll mail you a couple pieces.

 

[Lemensd]

No problem I've done it a few times on my prods, electric drill fine just take your time.

I've done both stepping up and main size first shot, stepping up was a little easier to stay true.

Replacements are cheap from Crosman, and you may want to experiment with different hole size's to find the best size for efficiency and power.

Enjoy

 

[Vetmx]

I use my lathe to do those tiny Crosman transfer ports. Just order one from Hill and keep your stocker just in case you want to go back to it some day.

 

[c_m_shooter]

I think yours is about the same as the Discovery transfer port. I drilled a few out with a hand drill and holding them with pliers.

 

[biohazardman]

For several years I did all of this with a hand drill, a Dremel, a couple of files and some 400-600 grit sandpaper. So, yes if you are careful you can do the same. 



22xx Valve mods

https://thegreencrosmanforum.proboards.com/thread/97/power-mods-valve-saved-archives

22xx transfer port mods

https://thegreencrosmanforum.proboards.com/thread/102/port-diy-power-mod-archives

22xx valve retention mod

https://thegreencrosmanforum.proboards.com/thread/73/22xx-valve-retention-posted-section

 

[FuzzyGrub]

I use a number drill set from Harbor Freight. Incrementally drilling larger keeps the hole well centered. Use some soft grip pliers to hold the TP.

 

[Feinwerk]

I hand drilled mine no problem. I put a piece of shoe leather in my vice and clamped it. I also called Crosman and ordered several factory units and then drilled them out starting with smaller sizes and working my way up until I got the performance I wanted. If you are recreating someone else's mod, and are sure of the size you want, then buying one ready-made is hitting the easy button.

I did a couple of things that helps me drill more accurately since I do not have machine tools. I got a circular bubble level and leveled my vise. My vise jaws have two Vee notches for clamping small round stock vertically. I chucked a small piece of bar stock in my hand drill and then clamped it in the vee notches in my vice. Then I used moldable epoxy to attach a circular bubble level to the rear end of my hand drill and adjusted it for level before the epoxy cured. Now I have a way to drill plumb by eyeballing the circular level on the back of the drill. If the back of your drill is not flat, use a rasp or coarse file to make a rough and flat area for gluing the bubble level.

 

[Jaje7654]

Thanks for the help. My electric handheld drill has a bubble level on the back which helped greatly in keeping the drill straight. I only eyeballed the level of the TP when it was in the vise, but the perimeter of the hole came out surprisingly even on both sides even with this crude setup.