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Question might sound real silly. I cut some square tubing to a length that i wanted, tacked it square and remeasured the lengths and they were all a little long. Is this something i need to account for? do these angles always end up a little long? Has anyone experienced this before and how should i compensate
Reply:Were the welds still hot when you took your measurement? Heat makes metal expand.Dont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Never even thought of that but I do think I measured cold. I will re measure tonight. It was on something that didn't need to be exact just don't want issues if something needs to be more accurate Sent from my SM-N900T using Tapatalk
Reply:What condition is your tape measure in? The hook on the zero end is designed to slide back and forth (the thickness of the tab) to compensate for whether you're pushing or pulling against it. If it gets worn out and sloppy it can throw your measuring off.
Reply:How far off were your measurements, in relation to how long you wanted them to be? Was it 1/16"-1/8" or greater than that? Did you account for the thickness/size of the pieces you were using, when cutting to length?Last edited by Bistineau; 06-04-2014 at 10:58 AM.
Reply:Measuring tape is in good condition it was pulled for both measurements so I don't think that's the issue. I may have measured hot I will measure again tonight Sent from my SM-N900T using Tapatalk
Reply:Also, did you re-measure the part after you cut it to make sure you made the cut on the right side of the line you marked?
Reply:When ever I want an accurate measurement, I never trust the clip on the end! I either cut an inch, or cut a foot.Dont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:I seriously doubt thermal expansion has anything to do with it. In order to make a 4ft. long piece of steel "grow" a full 1/16" you would have to heat the entire length up by around 200 degrees F and hold it there (that's 200 degrees F above the temp it was cut/measured at). Chances are, even if you measured hot, only the first few inches of the steel from the weld were more than 100 degrees above the starting temp. This would only account for a few thousandths (maybe 0.005") of expansion and would not be measurable with a tape.Most likely causes for your frames coming out long are: pieces were cut too long, pieces were not cut square, pieces not de-burred, sides of the tube are bulged wider than the nominal width, and/or improper clamping/work-holding during fit-up/tacking.To answer your original question, no, these joints do not "always end up a little long." This is what fitting is all about. You have to learn the difference between the lengths you think things should be cut at and the lengths that things should actually be cut at.Visit Tensaiteki.com
Reply:Before I built my new table to clamp parts down tight everything was done just laying on a plate. Had to build a frame for a tool and tacked the tops of the tubing, flipped it over and welded the back side. What I didn't realize is the tacks pulled the bottom side of the joint open and I welded it without knowing. The frame was now longer than the cut pieces.TOO MANY TOOLS & NO MORE SPACE
Reply:i have proved beyond any doubt that it is impossible to cut two things the same length..or even real close..make it up in the bead, or with a heavy hammer, or paint it dark..
Reply:Being a beginner my clamping system is lacking all angles were 90 degrees I measured 18 inches when all welded together it was a little over 18 guess I will pay better attention Sent from my SM-N900T using Tapatalk
Reply:You should be cutting on size or as much as 1/16 under. When you fit your material you check each end for square then insert the piece in your assembly. If you are short you can leave a 1/32nd gap at each end. If you are out of square you can tack the longest corner first and if you are still short tack the longest corner with a small gap. Cutting on size or longer will bring you heartache. Yes there are commercial machines of industrial quality that cut exactly square. In most cases these mythical machines have been operated by one person from new and the person actually read the operators instructions before starting.
Reply:Great question. I own probably the best quality welding table made and have a really good cold saw and I still have to under cut everything to get it to fit. In metric, I undersize by 1mm and in standard, I under size by 1/16 or 1/32 depending on the thickness and/or profile of the material I am working with. It also depends if I am TIG or MIG welding and that will determine how tight I need the fitting to be. Heat expansion has nothing to do with it.
Reply:I learned something in this thread. I guess heat doesn't make steel move. Attached ImagesDont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:I found out long ago that when I cut any miter to be welded I have to cut it 1/16" undersize in order for to keep dimension close to what I need, that is 1/16" per each miter ,easier to fill in than to recut
Reply:Originally Posted by CEPI learned something in this thread. I guess heat doesn't make steel move.
Reply:Depending on the steel tube size you have to cut 1/16 to 1/8" off your lengths
Reply:It was 5/8 16 Guage Sent from my SM-N900T using Tapatalk
Reply:Sometimes you may set your mark to the left of the say chop saw blade then next piece set it to the right . You could do that on a band saw table too . Depending what you cut with a stop can be set up for the same lengths.
Reply:Originally Posted by weldbeadi agree. i have been lookin at that foto for ten minutes and it aint moved..
Reply:Originally Posted by weldbeadi agree. i have been lookin at that foto for ten minutes and it aint moved.. |
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发表于 2021-8-31 23:09:30