The old Silca Impero pumps are plastic, and tap pretty easily. I've used a Bicycle Research crank arm extractor thread chaser for that.

Hey John,
I hope that you aren't going to hurt Rob's lucrative business enterprise with this post, I know we all have bills to pay.......
Best, Ben
BTW, Rob, thanks for offering this service.......

You are literally taking food out of my children's mouths. *





*OK, I don't have children. plus I'm offering a free service.

I also started with said crank thread chaser and cracked two tubes before I stepped up and bought my Swedish super pump tool.**




**OK, OK, I think the tool was actually made in the USA not Sweden, but I recently watched Austin Powers again.

Many years ago, there was a place in New York City with a sign: "Ears pierced while you wait."

Yeah, most place made you leave your ears and come back later.

My guess is that they meant they would take walk-ins, as opposed to having to make an appointment, but precision in the use of the English language is, for some people, not their long suit.

Oh, that could be. I assumed it was a joke, comparing their service to shoe repair places. They used to have signs that said "shoes fixed while you wait."

I have passed on all my Silka Pumps but what a great offer, Thank You.

I was accused in a PM of using AI to make that image (OK maybe "accused" isn't the best word...)
I'm here to tell ya, that is a screen-grab from a 1972 TV show, not edited at all, I swear!
Anyone know what show? You might be a nerd if you know this one. I'll leave it unanswered for a bit in case anyone wants to raise their hand.
I guess I should say "fellow nerd" since I absolutely am one.)

Rob,
As an incentive to increase traffic, perhaps offering a pump would help..........I need two, one sliver the other Gios blue.
Best, Ben
Also, pay shipping both ways???

I hadn’t a clue but there could only be one show in 1972 which would feature a bicycle pump shortening shop and a quick goggle turned it up:


Thanks for reminding about this sketch; I think of it all the time while out touring but haven’t watched in a long time. Here’s the whole thing:

Bingo! (Which is also a line repeated many times in the episode!)

But your YT clip is only "part 1" and they don't seem to have the rest. A full version is on DailyMotion:
https://www.dailymotion.com/video/x6qsd2w

I'm not a pump store.

I only have pumps for my own bikes.

You would pay to have the pump shipped to me, I add the threads. Surely you don't expect me to do this free service and pay to mail it back. toss in some stamps or a pre-paid label.

Because, of course, there is no need to shorten a Zefal HPX, as they come in different lengths, sizes 1, 2, 3, and 4.

But I salute the OP's contribution to the community.

R
Of course not....Just a yoke............I compliment you on your willingness to support the forum.
Best, Ben

I have a friend, while he doesn't have the longest legs, he really likes having the car seat all the way back.

I stopped by the Corvallis Bike Co-op one day and found what had to have been the world's longest Silca pump. I'm talking maybe a pump for a 65ctc bike (without umbrella clip!!).

At $5, thought it would make a wonderful gesture for my log legged friend Merziac.

I stick it in the safe haven that is the cubby area behind the rear seat. What could go wrong??

Thats when I let my friend sit in the back seat. My car is already rated as the "largest rear seat of any car not in a luxury group."

He reaches between his legs, lifts the seat slider lever and SLAMS if back to a large audible CRUNCH. It didn't just crack. it splintered. The rod was bent too.

Sure, it was only $5, and I was able to save the campy head and aluminum handle, but damn if that didn't piss me off.

The friend, I don't give him rides no more.

So someone suggested I also shorten the plunger.

sweetie's 71 Cinelli is a shorter bike. I measured and what I needed was 1” off the top.

I taped around where I wanted to cut. Pulled out an angle grinder with a cut off wheel and went to town. Grabbed a sanding sponge and leveled off any irregularities.

next I grabbed my fancy tool and added the threads.

inserted the plunger. I could see the markings of where or how deep it previously plunged.

took it to her bike. Compacted the handle down and nothing.

the plunger must have hit bottom. All I did was shorten the tube, but I didn’t make it fit any better.

Next attempt:

surely I can unscrew the plunger from the handle.

I went back down stairs to retrieve the broken one. I kept all the pieces minus the shattered tube. Pulled as hard as I could, but the plunger will not separate from the handle.

ok. Just have to think about this.

plunger out, I was able to unscrew the spring from the end.





next: I measured and again used tape to use as my cutting guide.

Out comes the cutting wheel. Soft aluminum was no match



[notice the dimples? More on those later]

once again I turned to my sanding sponge to take down any burrs



using a flat piece of marble, I was able to confirm the level of my cut. It’s clean.



now the tricky part. The putz or end piece needs further dismantling.

using a dremel, I make two incisions lengthwise being careful to only cut aluminum and not dig into the plastic that holds the leather plunger.

I see dimples where the aluminum has been punched to hold the plastic part in. I mark the now shortened plunger rod on 4 sides where I’ll punch it again.

with a screwdriver, I carefully free the plastic plunger tip from the cut-off rod end.

I insert it into the newly shortened rod and punch it on 4 sides. It holds steady. I bring the spring back up and screw it into place.

plunger shortened!!

screw the rod back into the tube and the whole pump fits onto her frame nicely.


Success

Your method is similar to Bob Freeman's except he shortens the outer tube from the bottom. He has a very informative Flickr album showing all the steps.
He uses a drill press as a sort of lathe at one point, to prep the plug at the bottom for gluing back in. Clever.
If you don't have a drill press, this step can be done by chucking the part in a hand drill, then holding the hand drill in a bench vise so you have both hands free. Material removal is done with a hand file, held against the spinning plastic, can be done very precisely. Remember to push the file through a full stroke; I see people holding the file still, but then you're only using one tooth (or a few), and that part of the file loads up and stops cutting.

BTW that drill-in-a-vise is useful for a lot of other things, a "poor man's lathe" — it can be used for lots of bike hotrodding tasks, like reducing the diameter of a bolt head. Combined with a hand-held belt-sander, can do cylindrical or conical grinding. Like sharpening the end of a thinwall tube to use as a leather punch. I just did that one the other day, drill-in-a-vise, even though I have a lathe, I just don't like getting abrasive dust on the precision ways if I don't have to.

Your method, tapping new threads at the top, doesn't need the drill or drill press, and is probably faster.

Ooh, maybe shorten the outer tube at both ends, so the Silca logo remains centered? Haha just kidding...

...or am I?

Have I shared this one before? Sorry if it's a repeat.
The best tap for Silca I've seen is the one Jim Merz made for himself. The reason it's the best is the pilot on the front of it, that fits snug on the inside diameter and forces the tap to go in precisely in alignment.

When he showed it, he said "it's a bit crude...". We should all be so lucky as to have such a "crude" tool!



Pretty sure Jim doesn't offer pump shortening as a free service though!