Looking for a 3/8-11 bottoming tap, cant seem to find and I cant get a local machine shop to make one.
Looking for a bottoming tap..
- Thread starter Russell Cues
- Start date
I guess I could buy another tap and have a shop grind the end clean and level....Just wanting to avoid more expence. I thought of doing the grinding myself but was concerned about grinding level and having burrs or anything that could throw off the tap.
I did this recently, and I was concerned about what you mentioned, but it came out ok I think. Tap first with your regular unground tap, and then follow with your ground one in order to get full threads as deep as possible. That way, your ground one is not the workhorse. I presume you are wanting this to keep your blind holes as small as possible/cut threads nearly to the end of the hole.
If you have a normal tool rest on a grinder, you can get your machinist square and a block of wood and possibly clamp the wood on the rest so you can have something in line to the wheel to hold the shank against while grinding the end.
Kelly
Easiest way is do it yourself and if it gets a little hot dip it water to temper it. I did mine free hand and it works fine using it as a second op tap.
Thanks for the advice, I have a grinder and I was apprehensive about the finished product but I will definitely do it myself then.
Cutting a tap
An easier way might be to place the tap in a vise and use a cut-off in a Makita like cut-off tool. Less heat and you can probably get it square. At least that
is how I did mine.
An easier way might be to place the tap in a vise and use a cut-off in a Makita like cut-off tool. Less heat and you can probably get it square. At least that
is how I did mine.
I ground mine myself also or should I say sanded it flat, the old Navy machinist I bought my first lathe (Atlas 54 inch gun lathe) from had built a huge sanding wheel to fit in place of the chuck. All I had to do was mount the tap in one of my boring bar holders and feed it to the wheel slowly and it worked great with a stream of coolant, looks like it would work well offsetting the tailstock also.--Leonard Holmes
Just had a thought, I could chuck up the tap and face it flat after I cut it off (dremel tool) with a cut off wheel.
I cut my 3/8-10 tap using a quality cutoff wheel (quick change style) in my dremel tool using one opf Todd's holders, with the tap in my mini lathe chuck. I squared the wheel to the chuck first, then took my time cutting slowly into the tap while it spun in reverse at 500 rpm. It cut great and there wasn't a need to face off the end of it. The important thing I noticed was not cutting into the full threads, but leaving about 1/16" of the shallower threads to be able to start the tap by hand a couple turns without cutting any wood. It all worked out well for me. Good luck.
Dave
Dave
When you cut the front off the tap, if the chamfer on the front is concentric to the thread,then it will be just like a brought one. Especially if it is backed off as well, instead of just a cone. The greater the lead of the tap,the greater it needs to be backed off.
I do mine on a D bit cutter grinder.
I do mine on a D bit cutter grinder.
I have a mini lathe (7x14) and thats what i was thinking, cut it off useing a dremel while its chucked up and then face it but if it cuts clean then all the better.