ST Slot?
 

I asked a fellow, Andy, the other day about a method of cutting the ST slot but neglected to ask about a dimension.
So I cou copy what is on my Surly but thought I would ask here.
Thanks!
Also it's time to do a shop cleaning!

I do mine on the mill, while I still have tube blocks attached from cutting the bottom bracket miter. I do a 1/4" hole 35mm from the top of the seat tube and a 3/16" slot, leaving it connected at the top until after reaming. After the frame is completed and the seat tube reamed, I cut the top section with a cutoff wheel and finish it with a file. I used to do an 1/8" slot, but I broke too many end mills cutting them and the larger slot doesn't hurt anything.


https://cimg4.ibsrv.net/gimg/bikefor...1fbd9cb31b.jpg

A mill is good but I use the real precision instrument: the angle grinder. The slot ends up about whatever width the cutoff wheel is. It doesn't need to be especially wide because you're only taking up a very small amount of diameter with the bolt. I make a little cylinder on the minilathe, drill and tap it to M6, TIG braze it on, and then cut the slit through the whole lot to join up with the hole. Because the cutoff wheel is quite thin I can then modify the slit a little bit with a dremel just to make it sure it hits the hole nice and centrally. Then I drill out one half of the cylinder with a 6mm drill bit so it's not threaded any more and the bolt goes in from that side.

A mill or an angle grinder is good, but I use the truest of precision instruments: hammer and cold chisel.

Okay, jk. I use a hacksaw with a new blade in it and cut twice. Before cutting, drill a hole at the end to reduce the chance of cracks forming. Starrett 32 tooth blades are the gold standard, but I am pretty happy with Lennox. A good saw frame is necessary to tighten the blade sufficiently that it doesn't wander. You should be able to clean up with a file if you get off-track. Some people use two blades, but I have never convinced myself to try that.

Just picked up a few new Lennox 32t blades. I need to ream first but will need the tap wrench from the bike shop.

perhaps a winter project is to make a handle for the reamer.

I use a hack saw quite often and being opinioned about my tools have decided to only use the type that have a tubular frame beam and don't use a wing nut acting on a pull bolt directly connected to the blade. These lower cost, often stamped beam, types have a lot of twist when sawing. Perhaps a small thing but when sawing all I can think about is how the cut is going. I think this helps explain why I don't double up a blade.

BTW if one does do a double bladed sawing pay attention to the second blade's tension. Most low cost hack saw frames have their blade engaging studs/posts at an angle, to better trap/secure a blade with. But if both blade holding studs are on the same side of the frame one blade will get tight before the other has seated on those angled studs. Andy

I like 2 blades on the frame. Tip, buy a stack of blades and pick through them, choose two that have their "wave set" in-phase with each other. If the set of the teeth is out of phase, kerf can get between the two blades and wedge them apart. Then they make two diverging cuts instead of one, getting further away from each other as you go, disaster if you don't notice it in time.

I like a warding file for cleaning up the hacksaw marks. It's about all I use a warding file for, so it's nice and sharp when I do need it. Of course you can just leave the hacksaw marks if you're not a princess, they don't hurt anything.

I mostly slit them on the mill with a slitting saw, but that's not faster, with setup time it's probably slower than hacksawing. So even owning a mill and a slitting saw, I might hacksaw some slits when I don't need the precision and repeatability of the mill method.

Like Andy said, you want a rigid hacksaw frame. I'm a big fan of the old Sandvik 225.

https://cimg2.ibsrv.net/gimg/bikefor...fe27d21d52.jpg

Spare blades can be stored inside the square tube of the backbone, plus you can set one in the backbone sticking out whatever amount you need, for sawing into a blind hole. Like cutting up a stuck seatpost for example.

Here's a 225 on ebay for $28 with shipping, just the first hit I got, not endorsing this seller. I recommend buying at least two so you can leave them loaded with coarse and fine blades, or one with two blades ganged up.

Sandvik is now Bahco. They have a 225 plus, but it doesn't look quite as nice as the one Mr. Bulgier posted. Same basic design though. Bahco sells some nicer hacksaws, but they are really proud of them, $60.

Lots of ways to skin this cat. I forget the thickness - 0.090" maybe? - but I use a slitting saw for ST clamps and stems. It's probably slower but it's more consistent.

Perhaps my winter project is to make a better hacksaw! When you say tubular frame, are we talking about a "junior" hacksaw here? That might be better for doing a seat tube slot anyway.

Here's how Doug did mine (hacksaw with (as I recall) doubled blades, tape)

https://photos.app.goo.gl/VyG4u7KJf5A94tYDA

Swipe right to see a few pictures of the process.

https://i.redd.it/lhh25okhf2e71.jpg

This is the style I use. One each for 14, 18, 24 and 32T blades. This photo isn't mine though, found this image on line. Andy

If I may nerd out about hacksaws for a bit — Some disadvantages of that type, compared to the Sandvik, as I see 'em:

1. Doesn't get the blade as tight. See how the pivot is halfway between the tensioning rod and the blade? so the tensions are equal, can't get the blade tighter than the rod, which tightens with a coarse thread and that smallish knob. Sandvik has leverage to make the blade tighter than the tension on the tightening screw, plus it's a finer thread which is like "low gear", and a knob that's easier to put torque on.
2. Stanley has loose, separate pins to capture the holes in the blade, that have to come out to replace the blade, and which can get lost. The one in Andy's photo has lost one of its pins. Blades just "fall on" to the fixed pins on a Sandvik, which cannot come out. Faster blade changes too.
3. I believe the Stanley can't take more than one blade, correct me if wrong. I have used 3 blades ganged up on a Sandvik a few times, a good ability to have in some situations.
4. Sandvik has another mounting position that holds the blade on a 45° angle that allows you to saw right flush to a surface (floor, wall etc.). I don't use it much but when you need it, it's brilliant. Example: one shop I worked at had a hole in the floor sized to fit a Pletscher kickstand. You'd mount the new, full-length KS on the bike, put the end in the hole and have a helper hold the bike at the desired lean angle while you saw off the end flush with the floor. Took two people but only a minute or less. Not possible with the Stanley, your knuckles would be dragging on the floor to even get close to flush, but you can never get the cut exactly right.
5. Blade storage in the backbone, not looking at it now but I think ten blades fit easily, probably more. Keep a selection of blade types there so you never have to go hunting for the right blade, or just a fresh one.
6. Blade inside the backbone, extended out some random distance of your choice, for sawing down into a hole when you can't hold both ends of the blade because a frame wouldn't fit. Pro tip: mount the blade with teeth pointing to cut on the pull stroke, keeps the blade straighter when it's unsupported at the end. You can buy a handle made for this type of blind-hole sawing, but the Sandvik is as good or better than those, and it's right there in your hands already. 10-second job to extend one of the stored blades and lock it in place.
7. No plastic. Plastic handles on Stanleys often break, as seen in Andy's pic. That one's not bad (yet) but I've seen 'em with the plastic handles completely gone.
8. From Sweden with Love! OK not really an advantage but it reminds me of the '70s Crescent ads with the very attractive model. That makes me happy. "Crescent Girl" must be in her '70s now, I hope life has been good to her.

Is there a PC equivalent to "swipe right"? I don't see any way to view any pics other than the one. I did like the pic though!

Sorry. I thought it would plop the viewer into that point of my album. If so, on a PC, moving the mouse to the left or right edge of the image should display a button with the appropriate pointing element ("<" or ">"). If not, here's the album:

https://photos.app.goo.gl/3YBkE6tGQRPsVwbS7

Click, swipe or scroll to your heart's content.

Nice, thanks. Pretty sure I looked at that album previously but it's fun to revisit it.
Sure looks like a Sandvik hacksaw in the maestro's hands, or a modern descendent of it (Bahco, or a knock-off?)

Tha KS for the album! I enjoyed Doug's class! Just finishing up my 3rd frame!

I tried posting a few pics but they don't want to show up!

I also drill the stress relief hole first and use a hacksaw, but rather than cutting twice, I mount two blades in the saw to cut a wider slot:

https://cimg8.ibsrv.net/gimg/bikefor...ce551bf642.jpg

John's photo shows the "low cost" blade tensioning design, a draw bolt having a stud. One nice thing about this is that the draw bolt can be flipped 189* so the stud points to the opposing side as the front blade stud does. This eliminates the untensioned blade I had mentioned before when doubling up.

My Craftsman styles do have a limit of one blade for the usual blade/handle alignment. But they do have a peg hole on the bottom of the holders where the plug can be inserted. So a second blade position at 90* to the usual is there and could be easily a doubled up location. Although actually sawing with the holder frame also at 90* to what you're use to will quite the effort and I would think not as controllable in the cutting action.

I have lost the Craftsman style pegs more that once (and bought used frames with missing pegs) but I have plenty of rod, nails and I have even machined a few too. NBD.

I see this "what hack saw is better" much like what kind of music is better. I'm happy to share the music I like with others but am happy with others liking types I don't (like opera). Andy

Oops I repeatedly referred to yours as a Stanley, dunno why, Stanley doesn't appear to have made anything like that Craftsman. I did see Stanley sells a Sandvik 225 clone that's painted yellow, so that might be what's in Doug Fattic's hand in smontanaro 's Flickr story.

Yep I hear ya. Some tools just "speak to you", especially if it's one you use really often like a hacksaw. They become old friends.

I have a Lenox hacksaw from the '70s that is exactly like Andy's craftsman except it's blue. It lost its blade holders bosses in the '70s, and I have been using nails ever since. I have a much newer Lenox that has the fanciest possible wingnut. The frame itself it quite stout, so it can tension the blade much better than the sheet metal saw frames everyone thinks of when mentioning wingnuts. I saw that Lowe's is selling a different Lenox that has a similar mechanism to the 225, except it's backwards, the knob is at the top of the handle. Milwaukee sells a seemingly identical saw in red. There is a Stanly that has an adjustment knob where the Sandvik lever is. Maybe next time I'm at home depot I'll look at it

Tom, cylinder hones come with different ball grits and different diameters. Several observations on slitting the seat tube in case there are any beginners reading this subject thread. First the seat tube needs to be reamed and honed before slotting. Otherwise, the slot allows the seat tube hole to open wider while reaming so it is temporally spreading the hole bigger rather than cutting it to size. Second, the slot needs to be about 30 mm long. I did a personal frame only 25mm long one time and I couldn’t get the seatpost to clamp tight. When I extended it another 5mm, the problem was solved.

My procedure is similar to bulgie’s using 2 blades together. I first somehow mark the slot to help guide making a straight cut. If I start to go crooked, I stop and use a slim warding file to straighten it. After I do the cut, I use the warding file to improve the cut. It is easy to break the file if sawing carelessly. What can happen is that if the file comes out of the slot and the point doesn’t go back in, your forward force will snap the file.

I don’t usually drill a stress relieving hole. I use a slim jeweler’s file with a U shape cutting teeth on the rounded edge and is smooth on the sides. This rounds the bottom of the slot so it isn't a stress riser. The problem with drilling a hole 1st is that it is difficult to get the slot to be right in the middle of the hole or the hacksaw blade scars the bottom of the hole with the last stroke. Of course, the hole can be filed larger to make the slot be in the middle and/or remove the scar.

The hacksaw is a very important tool and worth whatever it costs to get the right one. The hacksaw needs to feel comfortable in your hand. I like one that has a knob at the front to support my left thumb. I have 3 in the shop for different teeth per inch blades. 2 are branded Nicholson and the other one a Stanley. They are almost exactly the same and might be made by the same company. The Stanley’s yellow makes it easier to remember what blade it holds. They look like bulgie’s Sandvik except mine have a quick release blade mechanism. This method avoids the blade turning when tightened with a wing nut and allows me to get the blade very tight. I believe VAR makes a nice one too.

I send time with my students showing them how to properly cut with a hacksaw. A surprising number are awkward using one starting out. The students that took my framebuilding classes in the late 70’s came with more hand skill knowledge and ability than today’s younger student. There just isn’t as much opportunity to fix or make things today. Ukrainians are often better than Americans because they have a culture to try and fix things first.

I use Lenox blades from Lowe’s for convenience but by far may favorite brand are ones made by Bahco. What I really don’t like are hacksaw blades that are powder coated. It is always too thick and flakes off with the first use. Bahcos are painted with thin paint so you aren’t having to use extra force to get that thick coat through the slot. A few years ago Dremel came out with a series of quick release cutting wheels. These can do the job much faster but one has to be careful because it is easy to mess up the cut.
https://cimg0.ibsrv.net/gimg/bikefor...e87123b1d.jpeg
My tool wall next to my main vise

Yeah, I just leave that saw with two blades mounted. I have another saw with a proper tensioning design that I use for most work.

Doug's note about ST binder slot length is a good one and a trick I have used on production bikes to "fix" slipping posts at least a couple of times.

To key hole the bottom of the slot or not, that is the question... Having a stress riser free slot bottom is the goal, be that a hole or a U. I have filed a bottom "U" and it grow into a hole as I balanced the shape to much, over and over. Andy