would a dremel melt the inside of housings if I grind the ends with it?

[zmalwo]

I've read that people use dremels to clean up housing ends after cuts, would that melt the inside of housings? back when I first started building bikes I wrongly bought a dremel mini saw instead of a grinder and it would melt the teflon insides when I cut them. years later I learned that I bought the wrong tool. What other ways do I have to clean up housing ends?

[lhuerta]

....cut VERY quickly to avoid melting, then simply use icepick-like poker or other pointy object to open up the liner....done.

[GregL]

I use a Dremel grinding wheel to smooth the ends of cable housings after I cut them. I then use a small awl to open up the inner liner. Very straightforward with good results!

Greg

[slambers3]

Bench grinder. Usually just a touch is enough.
Use your bench grinder to sharpen the end of a spoke (make it pointy)
Use this to open up the cable liner. Save the pointy spoke for other shop tasks (comes in handy A LOT)

[Veloo]

Small nail, safety pin, paper clip will also open up the inner sleeve of cable housing if it's been deformed.

[arik]

Originally Posted by zmalwo

I've read that people use dremels to clean up housing ends after cuts, would that melt the inside of housings? back when I first started building bikes I wrongly bought a dremel mini saw instead of a grinder and it would melt the teflon insides when I cut them. years later I learned that I bought the wrong tool. What other ways do I have to clean up housing ends?

Take a small piece of scrap cable and insert it into the end of the housing you are cutting, then cut both the housing and the cable, then poke out the piece of cable in the housing, this ensures a clean cut and prevent the housing from collapsing or melting.

[dddd]

Modern derailer cable housing ferrules are designed with a soft inner face intended to allow the wires to embed to a proper degree based on typical cut-off angles on each individual strand.
This helps the compressive forces to equalize between adjacent wires, so that the load is shared and the housing doesn't deform under load.

It is my belief that there is thus no benefit to smoothing the ends of derailer housing after cutting.

Use of any sort of grinding stone or disc introduces a torrent of flying abrasive material into the housing's liner, which would seem to be the opposite of offering any performance enhancement.

As well, the housing polymer that holds the structure together gets extremely hot, which has it's own implications wrt the housing itself and the air that one might be breathing near such work.

Brake cable housings otoh can benefit from "squaring-up" work, but which can be done simply with a carefully-considered second cut to the uneven end of the housing using a standard cable/housing cutter.

So my thesis here is that using a Dremel on cable housing ends is at best a waste of time.

[Gummee]

Originally Posted by dddd

Modern derailer cable housing ferrules are designed with a soft inner face intended to allow the wires to embed to a proper degree based on typical cut-off angles on each individual strand.
This helps the compressive forces to equalize between adjacent wires, so that the load is shared and the housing doesn't deform under load.

It is my belief that there is thus no benefit to smoothing the ends of derailer housing after cutting.

Use of any sort of grinding stone or disc introduces a torrent of flying abrasive material into the housing's liner, which would seem to be the opposite of offering any performance enhancement.

As well, the housing polymer that holds the structure together gets extremely hot, which has it's own implications wrt the housing itself and the air that one might be breathing near such work.

Brake cable housings otoh can benefit from "squaring-up" work, but which can be done simply with a carefully-considered second cut to the uneven end of the housing using a standard cable/housing cutter.

So my thesis here is that using a Dremel on cable housing ends is at best a waste of time.

This. I'll run my spiral wound brake housing on the bench grinder (cause I'm too lazy to break out the dremel to cut the stuff) to flatten the ends IF there's an angled cut AND it's in my garage.

In a shop? Clean it up and put it on the bike.

If I'm cutting derailleur housing or compressionless brake housing, I don't bother.

As with everything, people can overthink mechanicing...

M

[Mark McM]

Originally Posted by dddd

Modern derailer cable housing ferrules are designed with a soft inner face intended to allow the wires to embed to a proper degree based on typical cut-off angles on each individual strand.
This helps the compressive forces to equalize between adjacent wires, so that the load is shared and the housing doesn't deform under load.

It is my belief that there is thus no benefit to smoothing the ends of derailer housing after cutting.

Use of any sort of grinding stone or disc introduces a torrent of flying abrasive material into the housing's liner, which would seem to be the opposite of offering any performance enhancement.

On the other hand: Not all housing ferrules have soft inner faces, and there are some shifters that don't use ferrules at all (such as Campagnolo shifters). Also, there are some cable systems that used continuous liners that aren't installed until after the cables are cut and finished, so introduction of debris into the housing makes less difference.

[HenryA]

Originally Posted by arik

Take a small piece of scrap cable and insert it into the end of the housing you are cutting, then cut both the housing and the cable, then poke out the piece of cable in the housing, this ensures a clean cut and prevent the housing from collapsing or melting.

This^^^^^

And use good cutters. Done.
If its not perfect enough, then an old spoke sharpened to a point will help to smooth out the end.

[teleguy57]

Dremel works well for me.

As for picks, my friend the pro mechanic takes some winter down time and plays with making new picks etc for himself from all sorts of interesting things around the shop, including ti and carbon spokes. Various sizes, bends, degree of pointy-ness, weight balance etc. Truly cool stuff!

[arik]

Originally Posted by HenryA

This^^^^^

And use good cutters. Done.
If its not perfect enough, then an old spoke sharpened to a point will help to smooth out the end.

Yes I have skipped the dremel these days, but I use the best knipex wire cutters (felco when I'm in the mood, I can't resist tools). I am surprised cutting the housing with a bit of scrap cable in it hasn't caught on, but bikes barely use cables anymore.

[bikinchris]

I have always used a bench grinder to finish housing ends (both brake and shifting), then a Dremel with a pointed burr to open the inner liner. Sometimes, it was necessary to use a machinists scribe to grab the liner to make it easy to use the Dremel. Did it dozens of times a day.

Just twist the cable housing while grinding gently to make it square. It improves shifting performance and greatly improves brake feel compared to letting the housing end stay crooked.

[dddd]

The other thing is that there should never be any high tension force on a derailer cable when it hits the road.

Especially with regard to the lo-limit screw setting, one should always adjust so that no added force is needed to shift to the largest cog, else the cable becomes prone to rapid fatigue in use.

So again, there should be no need for any housing cut finishing, and the usual pre-stress prior to final adjustment should amply suffice.

This from someone who did cut some of these housings using a Dremel back in the day!

[Ronsonic]

I once had a dremel cut-off wheel snag a strand of compressionless housing - caught that and just shredded the thing. Wadded about ten inches of it into an impossible snarl before I could get the thing stopped.