u/whimsyedge1

I’m still new to plumbing stuff. Just trying to fix small things at home, nothing serious. As of recent, I had to replace a small section of pipe under my sink. I watched videos and they made it look very easy.

My issue is cutting the pipe clean.

I used a manual cutter first. It worked but the cut was not very smooth. It had small rough edges and I think that’s why I got a tiny leak when I joined it back.

Then I saw people talking about cordless tube cutters (SPU). I don’t fully understand if it makes a big difference or if it’s just for professionals.

I almost ordered one online. Even checked Alibaba because price was cheaper there, but I got confused reading reviews. Some people said it works perfect, some said it stops working after few uses. So I didn’t buy yet.

My questions are, Do I really need a powered cutter for small home jobs? Or is my problem just bad technique? Should I also be sanding the pipe after cutting?

Also, how do you know when the cut is “good enough”?

I don’t want to keep guessing and causing more leaks 😅

Thanks in advance, I really appreciate any simple explanation.

I want to ask if anyone here has experience with older equipment slowly changing behavior during production run.

We run a small injection molding machine in a workshop environment, nothing modern, hydraulic, probably the ones built in the early 2000s. The machine runs fine during the first hour. The parts fill clean, weight stable, cycle repeatable. After maybe 90 minutes things start acting strange.

Material is PP homopolymer, dried properly. Cold runner mold, single cavity container lid. No valve gate. Shot size about 65 percent barrel capacity.

Problem is not classic short shot. Instead part weight starts drifting. First heavier, then suddenly lighter. Cushion changes even though screw position setting not touched. Barrel temps stable according to controller but melt feels different when purging.

We checked back pressure, screw rotation speed, clamp force. Maintenance team cleaned check ring last month. Still same behavior.

Funny thing is I once bought spare heater bands from Alibaba because local supplier quoted crazy price. They worked okay but one failed early so now I don’t know if temperature feedback is lying to me. Sometimes Alibaba saves budget, sometimes you learn lesson slowly.

Hydraulic oil temperature climbs after long run, around 55°C. Could viscosity change cause inconsistent injection speed?

I am trying to understand if root cause is thermal expansion, worn screw, or hydraulic response delay.

Anyone seen machines behave perfect cold but unstable once fully warmed up? What should I check next before pulling screw assembly out?