imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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I have a tube cutter puchased at Home Depot. It seems pretty standard and no frills, just two rollers on one side and the cutting wheel on the other. I have made three practice cuts on a silver anodized Moonlite truss tube, just little 1" pieces. The rollers are leaving some pretty ugly bands around the tube on either side of the cut. It is bad enough that I can't buff it off after cutting.
First I tried laying down a layer of electrical tape for the rollers to travel on, but the tape got bunched up. Next I tried lubing the rollers with 3-in-1 oil, but I didn't have any effect.
Is there a way I can prevent the banding from the rollers and still cut the tube with this tool?
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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dave b
Post Laureate
Reged: 05/10/05
Posts: 3534
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are the rollers mirror polished or are they rough and grooved?
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dave bonandrini
30" f/5.2 Dobsonian
President of GCAC
Astromart Moderator
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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The rollers are smooth. Yeah I mean if they were rough or grooved that would obviously explain the results I'm getting.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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This is it:
TUBE CUTTER
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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Don W
Postmaster
Reged: 05/19/03
Posts: 14621
Loc: Wisconsin, USA
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I don't think you're going to get away from that with that type of cutter. Those rollers are putting a lot of pressure on the tube to hold it in place for the cutter. If you put this end of the finished tube in the base clamp of the scope will the marred finish be hidden?
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Don Wyman
Obsession 18" f/4.5 #1166
W/Argo Navis DSC and Torus Primary
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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Quote:
I don't think you're going to get away from that with that type of cutter. Those rollers are putting a lot of pressure on the tube to hold it in place for the cutter. If you put this end of the finished tube in the base clamp of the scope will the marred finish be hidden?
All of the clamp fittings I'm using will leave the marring revealed unfortunately.
Ok, I will probably try to cut them on a power miter saw. I've got a blade that's worked will in the past on larger aluminum tubing. I also have a 10" black cutting wheel.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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Owen
professor emeritus
Reged: 06/21/07
Posts: 514
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You're over tightening the cutter...
Quarter turn using fingers - 2 or 3 turns around the tube, repeat until its cut...
Have fun
Owen
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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Owen, actually I tried that as well. I have to crank it down pretty tight to keep the wheel cutting straight. If I loosen it like you're saying it actually angles just slightly and then I end up cutting threads that walk down the tube rather than a single groove. Maybe I have a bad one...
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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Owen
professor emeritus
Reged: 06/21/07
Posts: 514
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That sounds like the cutter wheel hole is too large.. quite common - practice will make you more familiar with its oddities...
I use mine for copper work - and until I had mine worked out, it would either cut an irregular screw thread, or marr the surface of the tube.
Key is finding enough tension to keep all square, but not too much to mark the workpiece... 
Try messing around with some copper, to dial it in a little..
Have fun
Owen
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BCB
Undercover Saboteur
Reged: 11/24/03
Posts: 5196
Loc: Look over your shoulder
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Tube cutters unfortunately have the tendancy to "roll" over the edge a bit. Looks like a burr, but isn't very rough.
Easiest way to get rid if it, is to spin the tube on a table, and use a large fine file to gently remove the lip. Once that's done, then go back over it with a piece of scotch bright to clean up the file marks..
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Mark
Lost in thought. Please send search party!!!
Astro-Tech 111EDT
Orion 8" F5 Newt w/Moonlight CR-2 focuser
SVP mount w/Meade 497 Autostar GOTO mod
Treeline Observatory
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gregj888
sage
Reged: 03/26/06
Posts: 301
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Curt,
You might also try a layer or two of duct tape or plactic tape on each side of the cutter poition. You'll have to use light pressure but it works fo a lot of things.
I just used the same trick on a piece of Al. I wanted to polish in the lathe. A few turns of masking tape and no chuck marks...
Greg
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scopemankit
super member
Reged: 01/27/09
Posts: 137
Loc: south africa
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Use a 1.5mm thick metal cutting disk on an angle grinder!
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Chris
Cape Town
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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I should have posted a photo because I've confused everyone. Sorry about that.
Quote:
Tube cutters unfortunately have the tendancy to "roll" over the edge a bit. Looks like a burr, but isn't very rough.
Easiest way to get rid if it, is to spin the tube on a table, and use a large fine file to gently remove the lip. Once that's done, then go back over it with a piece of scotch bright to clean up the file marks..
I'm not getting a burr really, but yeah the edge that is cut needs a little touching up which is easy. My problem is different. About 1-2 cm inward from the cut there is a band of scuffed up metal where the rollers on the tube cutter are applying so much pressure that they scuff up the anodizing.
Quote:
You might also try a layer or two of duct tape or plactic tape on each side of the cutter poition. You'll have to use light pressure but it works fo a lot of things.
I tried this, mentioned above, but I used electrical tape instead. I guess I could try duct tape, but actually it is thicker and would place a larger gap between the tube and the cutter when the rollers contact it, so I'd have to apply more pressure than before, and I'm guessin it will bunch up worse than the electrical tape. Just thinking logically about it....
Quote:
Use a 1.5mm thick metal cutting disk on an angle grinder!
Ha...well I need something I tad more precise than hand-holding the tube up to a grinder.
Thank everyone for your thoughts. I think most people probably use standard, unfinished aluminum tubing that already looks pretty raw, so my problem isn't an issue. But I'm using anodized metal that looks nice. I'm going to use my mitre saw with an appropriate blade. The tube cutter is a total disappointment.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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Jim Romanski
scholastic sledgehammer
Reged: 01/02/05
Posts: 843
Loc: Guilford, Connecticut
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I have the same tubes and a similar cutter. I cut them about 2 years ago and I remember using masking tape to prevent this. I see you've tried electrical and others suggest duct tape so you might continue to experiment.
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Jim
17.5" Dob "Project"
13.1" Coulter
8” Cave
NP 101 on a CG-5
25x100 binos
Naglers, Ethos, etc.
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dave b
Post Laureate
Reged: 05/10/05
Posts: 3534
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the fact that if you cut it with the tension loose, it walks and cuts threads makes me you think you have a bad unit.
i just tried to make a super light pass with my 2" rigid and it did not walk at all.
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dave bonandrini
30" f/5.2 Dobsonian
President of GCAC
Astromart Moderator
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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Ok fair enough. I need to buy another one and give it a shot. Mine actually is not the Rigid, but it's a clone of that exact tool. They are identical to look at, but....
I'll buy one after work today and report back.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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And now for the exciting conclusion...
I bought a different brand of tube cutter at Lowe's and repeated my trials. There is definitely a threshold of tightness that needs to be reached before you try rotating the tool. Both of my cutters are prone to walking down the tube if they are too loose.
This new cutter unfortunately leaves marred bands on my anodizing just like the first one did. Every kind of tape I've tried just gets bunched up.
Bottom line - tube cutters are no good for nice tubing. I can see how they are more than adequate for copper and raw aluminum where scufs don't matter, but it's all wrong for my application.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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dave b
Post Laureate
Reged: 05/10/05
Posts: 3534
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one scary thought is that the anodizing is not completely sealed.
boil a pot of water and throw a piece of scrap in for 30 minutes. see if the cutter still leaves marks.
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dave bonandrini
30" f/5.2 Dobsonian
President of GCAC
Astromart Moderator
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Nathan F
sage
Reged: 10/10/08
Posts: 221
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Sounds like a chopsaw and metal cutting blade might be the best way to go...
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12 inch f/5 Deep Space Observer Dob
31mm Nagler, 13mm Ethos, 1.6x Antares 2 inch Barlow
Celestron SkyMaster 15x70 Binoculars
Homemade Maple Parallelogram Binocular Mount
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gregj888
sage
Reged: 03/26/06
Posts: 301
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My Home Depot cutter will aslo cut threads. Instead of making complete turns I go back and forth making going just over one full revolution. It works for me.
Greg
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