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Letter 50046
Please help with satin finish on stainless angle
September 21, 2008
To anyone who can help, we are an ornamental metal fabricator currently trying to put a #4 finish(longitudinal) on stainless structural shapes, i.e. angle and channel for a big project in our area. we have been trying with sanding discs, belt sanders, die grinders,
and an inflatable rubber sanding head on a stright shaft grinder using 36 thru 120 grit
belts and wheels etc. However, there seems to be so many imperfections in the material from the mill it is taking countless manhours and we will never meet our deadline. Does anyone have any suggestions? The real problem is we are trying to finish the inside of the 3" channel and angles.
STEVE MILLER
Metal Fabricator - Coraopolis, Pennsylvania
^- Privately contact this inquirer -^
September 23, 2008
To get consistency, you should look at a pass through system. You can buy or build one yourself if you only have 1 or 2 shapes and more than likely you will have a series of fixed wheels. Type of wheel depends on finish you desire. During operations you should monitor pressure and/or contact.
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AF Kenton
Huntingdon Valley, Pennsylvania
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September 23, 2008
Steve, AF Kenton is right on with recomending a wheel machine. Some mills, have this capability to process structural shapes through a wheel machine to remove mill scale. You should check with the Mill you purchased from. You definetly would want the Mill to use a stainless media, say stainless cut wire shot, so iron is not imbedded into the stainless shapes. A conditioned cut wire shot would give a burnished "peened" appearence if this is acceptable. I believe there are some specialty Mills in Pa. with the capability to do this, it's worth a call. Good Luck.
| December 10, 2008
Steve:
I understand your problem as we do the same thing and nearly all my finished stainless is #4 brushed.
I agree with going to the mills for help if time is on your side. I have tried that and usually they quote weeks to furnish special finishes.
If your customer is amenable to the idea you may want to consider fabricating the angles & channel from flat bar. Also time consuming but if you have the problems I have it's the easier way to go as most of my projects call for irregular legs such as 3.75" x
4.375". They don't make angle to those specs. We do the finish on flat bar, inside only, then tig and go back to refinish the weld with die grinders, hand finish or as you have found. Whatever works. No fun any way you look at it.
CS Unitec makes a tool, It is a drum type hand held. If you have a Metabo, Unitec makes the normal size drum that you can adapt to your Metabo. We have 2 Metabos #SE-112 which is the kit. We made guides to keep our brush stroke straight and uniform. We us 60 Grit flap discs to get out the mill streaks but you should try to use Type 29 discs which don't have the tapered disc surface. They are flat across. Don't tip the grinder at an angle. keep it as flat as possible and work so that the sand scratches follow the longtitudinal grain which means you work the grinder across the part rather than working the grinder lengthwise down the piece which makes the sand scratches perpendicular and even harder to work out.
Wayne Petry
- Buffalo, Texas
September 20, 2009
Hey Steve,
You may need to look into a machine called a "Timesaver" while Timesaver is a brand of its own these type of machines have adopted this name. We built our own. Basically its kind of like a stationary planer but instead of a rotating blade its a vertically positioned sanding belt. They can be configured with 1,2,3... belts as to allow a one pass system. Widths are only limited to the widths of sanding belts available. The main points to consider if making your own is:
1.) Controlled pressure of the drum on the part
2.) Controlled feet per minute of the part through the machine.
3.) Controlled belt centering (system to keep belt on drum)
4.) Controlled rpm of drum
Cliff Kusch
electropolishing shop - North Vancouver, British Columbia, Canada
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