couple of questions regarding tube thickness, brazing and milling

[steve garro]

I'm just guessing at 1200, by the way - I normally use the top speed on my drill, but not always at full throttle. I find I can feel if it's sawing nicely through or not, and vary speed and pressure as I go.

I guess what this shows is there's no right answer ;-)

Yes there is - you just don't know it.
You just said so.
You're just using a dewalt hand drill and a jigger & guessing, right?
Day & night from a real milling setup.
My mill has been set a 240RPM for thousands of tubes.


18bikes has it going on right there, great suggestions esp as per thickness = a 7/4/7 OX Plat will be way more scary then a 1/7/1 Supertherm even though they are the same alloy.

- Garro.

[bencooper]

Yup, you're right, I've been just guessing for 15 years of professional framebuilding. But hey, thanks for your patronising answer

[steve garro]

Yup, you're right, I've been just guessing for 15 years of professional framebuilding. But hey, thanks for your patronising answer

Your words, not mine.

I'm just guessing at 1200, by the way - I normally use the top speed on my drill, but not always at full throttle. I find I can feel if it's sawing nicely through or not, and vary speed and pressure as I go.

I guess what this shows is there's no right answer ;-)

I'm not a patronising type of person, but guessing/assuming is not fit for a thread aimed at actual dissemination of factual knowledge to build object on which peoples' lives depend, right?
You don't own a mill, right?
- Garro.

[bencooper]

I do own a mill - it's a small one so not brilliant for mitring. I also have a couple of lathes. Is this a "I own more expensive kit than you do" willy-waving contest?

Okay, a simple thought experiment. Take a chainstay - most people can hacksaw through a chainstay in 30 seconds or so, without causing any problems at all, right? Now a hole saw is just a hacksaw blade welded into a circle, and is about the same effective length, so whats the difference between hacksawing though a chainstay in 30 seconds and hole sawing through one in about the same time?

[steve garro]

A) "I own more expensive kit than you do" willy-waving contest?

B) so whats the difference between hacksawing though a chainstay in 30 seconds and hole sawing through one in about the same time?

A) That is SO not me.
I barely attach any value to objects.
People, yes.
Objects, no.
I'm not going to win any "Willy-Waving" contests (That's so cute, BTW)

B) Accuracy, repeatability, less wear & tear on the body, the ability to miter both at once to perfect length & with offset on the BB shell?

I'm not busting chops, I just so want this to be a source for reliable info.
- Garro.

[bencooper]

Okay I misunderstood your comment about a mill. As I'm sure you know, results are what matters, and you can get equally good mitres with a hand file, a hole saw, a milling cutter or a full CNC setup. The only difference between those methods is the speed of manufacture, not the quality of the result.

My hole saw setup provides high accuracy, repeatability, and the ability to miter at the correct length and offset. What it might do, because hole saws aren't designed for this job, is go through cutters at a faster than optimal rate. But they're so cheap that's not a big issue - if a £9 hole saw only lasts 1/4 the time a £120 milling cutter does, I still win on price.

I like this to be a source of reliable info too, and an important part of providing reliable info is describing methods and techniques that have been tested and work.

[steve garro]

Okay I misunderstood your comment about a mill. As I'm sure you know, results are what matters, and you can get equally good mitres with a hand file, a hole saw, a milling cutter or a full CNC setup. The only difference between those methods is the speed of manufacture, not the quality of the result.

My hole saw setup provides high accuracy, repeatability, and the ability to miter at the correct length and offset. What it might do, because hole saws aren't designed for this job, is go through cutters at a faster than optimal rate. But they're so cheap that's not a big issue - if a £9 hole saw only lasts 1/4 the time a £120 milling cutter does, I still win on price.

I like this to be a source of reliable info too, and an important part of providing reliable info is describing methods and techniques that have been tested and work.

I agree with you.
FWIW a "standard" cutter like a Starrett or Lenoxx (what I use) will last until you are sick of it *IF* your setup is without flex or you will blow off teeth, which are catching on the tube - sure, some hole saws suck & last a couple cuts (not many) but I just have to eventually say "these are dull" and pass them on to my Al. working friends :)

I hand mitered >50 fillet frames when I started - I don't have the elbows or shoulders for it - too much Willy-Waving I reckon...... :)

...........More then three shakes & you're playing with it ;) ................

- Garro.

[EnginCycles]

Here is something I will add that might shed some light on the situation of milling.

The bigger and more robust the machine the slower you can run the RPM and the harder you can feed (or feed rate). The more robust fixture is only as robust as the weakest link between the part and the floor. If the machine is clapped out and light duty the most robust fixture will only tell you where those machines are clapped out. A weak fixture on a totally stout machine will also tell you the fixture has limitations. With all that said the speed rates and feed rates are going to be in the ball park of the suggestions but the final # will be adapted to the end user. My set up is almost always running at 293 RPM with a feed rate of 1 inch per minute. Power feed is the key to running a slower RPM since it can be controlled to keep feeding. The power feed also requires EVERYTHING to be robust since it won't stop and your emergency stop (you panicking and hitting the stop button) will be too late.

I have tried all types of machines from small clapped out to my Cincinnati which weighs 5000lbs. The quality of the miter you get with power feed and an extremely robust machine and fixture is hard to beat. I am not saying my set-up is better than others. Just saying what I have experienced and trying to explain the difference between set-ups.

Also just a note. Until you have mitered 953 you have not experienced what a hard material that snags is. Sub .6mm thick and rock hard. AerMet is a close 2nd with S3 not far behind. All three can annihilate a hole saw in one cut. Missing teeth and in the garbage before even finishing the miter.

[Amaro Bikes]

Until you have mitered 953 you have not experienced what a hard material that snags is. Sub .6mm thick and rock hard. AerMet is a close 2nd with S3 not far behind. All three can annihilate a hole saw in one cut. Missing teeth and in the garbage before even finishing the miter.

Hi Drew, I recon XCR would be pretty much the same, right? In this case, I assume handmiter is out of real world behaviour with stainless steel tubes? I was thinking of making first experiments by the end of this year, but would be suicidal by hand?

Cheers

[EnginCycles]

Hi Drew, I recon XCR would be pretty much the same, right? In this case, I assume handmiter is out of real world behaviour with stainless steel tubes? I was thinking of making first experiments by the end of this year, but would be suicidal by hand?

Cheers

XCR is not anywhere near a super steel like the others. It is however more stainless than stainable like 953. All can be mitered the same way just keep in mind you will ditch a file faster, a blade sooner and go through more of a grinding wheel. Rigidity is still key here. A pedestal mounted vise that is bolted into the floor with a proper wood block will allow for faster hand mitering than a wobbly bench with a crappy vise and a loose block.

[arregui]

I'm just guessing at 1200, by the way - I normally use the top speed on my drill, but not always at full throttle. I find I can feel if it's sawing nicely through or not, and vary speed and pressure as I go.

I guess what this shows is there's no right answer ;-)

claramente!!!!

[Amaro Bikes]

XCR is not anywhere near a super steel like the others. It is however more stainless than stainable like 953. All can be mitered the same way just keep in mind you will ditch a file faster, a blade sooner and go through more of a grinding wheel. Rigidity is still key here. A pedestal mounted vise that is bolted into the floor with a proper wood block will allow for faster hand mitering than a wobbly bench with a crappy vise and a loose block.

Hi Drew, thanks for all your inputs.

Ok, I though xcr was on the league of 953. For the mitering, I'm not so worried about the setting (bolted industrial workbench including the heavy weight vise, and both wood blocks and paragon's alu tube blocks), but for the actual tool wear (files/hacksaw) or time consuption on handmitering. I already knew titanium is almost an impossible mission to acomplish purely by hand, but I thought stainless steel would be a bit more friendly.

Cheers.

[arregui]

Some months ago Aimar gave me in this thread different solutions to sleeve a ST for the ST/TT joint. I was not familiar with the following technique as i thought it was only a TIG thing:

Hola, Andrés.

-Use some of the special seat collar/sleeves as ones made by paragon intended to work as top seat tube, so you just braze or weld this part on top of seat tube and this would be the area for tt and ss to end. This sleeve is also available on different diameters and are quite thick. One example:




Cheers.

Anyone is using this sleeve just brazing (no TIGing).
Would love to see a photo of this.

Thanks to all!

[Eric Estlund]

I haven't used the Paragon unit, but have made similar sleeves in the past. I made my own to fit the dimensions I needed for the project.

[Jonathan]

I've used the paragon option on a handful MTB frames. I tig welded though. Out of the box the fit will be too tight to flow even 56% silver. Other than that they work well, though I wish they were 20mm longer. If you can make one, that's an even better option.

[Todd Mosley]

Remember that they are stainless except a steel sleeve for a 35mm seat tube. If you are fillet brazing you'll need use silver to join the top tube and seat stays.

[arregui]

Thank you very much for your answers.


Eric, Do you have any pic of the process?

Jonathan, nice point. I bought one to see the dimensions and have an idea but i plan to make mines. I was thinking of lug+56% tolerances.

Todd, got it!, have a nice fillet pro for that.

[Will Neide]

I used a preform ring on the inside and pulled the silver from the inside out the one time I used the paragon sleeve.