M10x1.5 thread tapping
M10x1.5 thread tapping
(OP)
I am trying to tap a 3/8" mild steel plate for a M10x1.5 thread but after the tapping process the screw is has too much play. We are using a .336 in. hole and a M10-1.5xD5 3 flute spiral tap. I am new to metric threads so am not familiar with the tolerance classes. Could someone please suggest an appropriate process, drill, and tap?





RE: M10x1.5 thread tapping
RE: M10x1.5 thread tapping
You didn't mention if this was being hand tapped, or done on a drill press or CNC machine. If hand tapping, switch to a more stable process with a fixtured drill press, or CNC.
"The attempt and not the deed confounds us."
RE: M10x1.5 thread tapping
RE: M10x1.5 thread tapping
RE: M10x1.5 thread tapping
Below are some links that might help.
http://www.boltscience.com/pages/screw8.htm
http://www.newsontool.com/01_16-17.html
"The attempt and not the deed confounds us."
RE: M10x1.5 thread tapping
are you drilling the hole using an alignment bushing? are you spot drilling the hole prior to drilling? if not, you could have a condition where the hole could be oversized for a bit at the top of the hole. since you are drilling 3/8" thick plate, the drill will not have enough material to "straighten" itself out. basically, your hole may be egg-shaped.
what type of tapping fluid, if any, are you using? sometimes when tapping low carbon steel, the material will gall or stick to the tap causing the threads to be oversized. you can fix this by using a tapping fluid with higher amounts of sulfer to help with the galling.
i would strongly suggest that you by a go-nogo gage to properly check the threads. standard metric threads are 6H/6G.
the 8.5mm drill you were using in the beginning is the proper drill size and i would not deviate from using this size. just double-check the hole size after drilling to see if is correct. we produce these threads every day with no size problems. we use a 8.5mm, solid carbide, through coolant guhring drill. we use YMW taps and our threads have an effective depth of 20mm(3/4").
hope this helps a little.
RE: M10x1.5 thread tapping
Make sure your tap is sharp.I assume that you are using a "tapmatic" type tapper. Make sure it is not wabling all over the place. Make sure your clutch is set properly.
You are either "wallering" the hole during the drilling process or cutting too much material in the tapping process due to some other variable.
Reducing the tap drill size will only buy you so much.