Any advice on best techniques, tools, length I need to leave etc in advance please ??
- in the industry
- Posts: 2990
- Joined: Sun Nov 21, 2004 2:45 pm
- Location: London, UK
When you cut, cut from one side to the halfway point then rotate 180 degrees and cut the rest. This avoids damage at the end of the cut.
You need a guide and a cutting blade, some tape if you like and some sand paper.
Use this cutting guide Threadless Saw Guide - #SG-6 or make one yourself. You can also use a miter box
Use a 32T cutting blade.
Use some tape to wrap around the area you will cut through to avoid any splintering of the carbon.
Cut slowly with even straight strokes.
Do not force the blade while cutting. Let it cut.
Do not force the steer tube just let it fall off as you cut.
Use the sand paper to plane the top if needed and remove any burs.
A very fine hacksaw blade works as well as anything, the best thing I've found.
I've used a miter guide twice and neither time was the cut perfectly square. Next time I'll either buy a cutting guide or fashion one out of hose clamps.
The times the cut didn't come out square, it was easy enough to square it up with a flat file -slowly, checking w/ a square on two different axes, etc. Took about 5-10 minutes. It really wasn't a big deal, but the cut wasn't too far off to begin with.
It's really not a technically tough thing, but if you mess it up, it's a high price to pay. I recommend doing a practice cut (i.e. cut the tube long just to practice).
Measure twice cut once - use the method described above (actual installed length with spacers and stem). Follow the fork and/or plug manufacturer's recommendations as to length. Some require a couple mm below the stem, some recommend cutting it 3 mm longer than the top of the stem so you can put a 5 mm spacer on top of the stem and the tube will be about 2 mm shorter than that. There is no "standard" way of doing this, it depends on how the plug interacts with the stem. I've had both types of instructions.
1) Put tape on the tube. Mark off the height all the way round the tube. This is critical as if the hacksaw wanders off you need to be able to see it and stop cutting.
2) Clamp the tube so it doesn't move. It's impossible to make an accurate cut if the fork is wiggling around on a desk.
3) Use a seat clamp, stem, fork brake hanger or similar as a cutting guide. Clamp it near the cut line then add a cheap stem spacer to guide the blade. Of course a Park tool version is better, but not worthwhile if you only use it every 3 years.
4) Cut slowy. If it goes a bit off line, stop and start from another position. Cut right through without attempting to snap off the last piece. As it's all fixed down, this is easy.
5) Leave the stem spacer where it is or move it down 0.5mm. Use it as a guide to file the top completely square.
A cut off saw. The kind made for metal. It seriously leaves the best cut I have ever seen. Go slow and it practically melts through the back side.
Other then that wrap the tube with electrical tape and cut away. Cut a bit in from the backside to avoid splintering.
Even cutting "slowly" it is increadibly fast and leaves a perfect 90° cut with no splintering.
But I have also used a fine-blade metal blade in a hack saw. This is much slower and effort-intensive, but works.
I always smooth the cut end with fine (400-600 grit) sandpaper and make sure therre are no delaminations or chips .
Yes, wear a dust mask.
As far as the mask it is a pretty good idea. I usually have black snot for a day if I don't wear one. evidence enough that there fine airborne particulate you probably don't want in your lungs. well anymore than following a city bus i guess. It's not like we are mining coal for 10hrs.
So, fair warning, slow waaaay down at the end, or flip the steerer 180 degrees at mid cut. This is something I've always done when cutting with the hack saw, but thought it wouldn't be necessary with the sawzall.
Anyway, my question is two-fold...
1. Ride it? Repair it? Bin it?
2. Repair tips for epoxy resin in this type of job?
Cielo by Chris King Cross Racer
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