No Spotting bit...what to do

Splat

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Don't you hate when you know you're forgetting something and you don't realize until all the places you could go to get what you forgot are closed. :mad: I was at McMaster today to pick up a bunch of things and I forgot to buy some spotting drill bits. I'm wanting to make a sleeve for a 1/4" boring bar to fit my QCTP. I do naturally have some center bits and know their 60º isn't good to use (except the tip) and I have a few small bits but I think they're all 135º. Should I hold off until Tuesday to get some spotters or what can I try to get the hole dead centered and true? Thanks guys.
 
I wouldn't wait, have at it. Use the center drills & don't worry about. I still use center drills sometimes even though I have spotting drills now. Or don't even worry about spot drilling. You're only using the drill bit to rough out the hole anyway. You should finish off with a boring bar.
 
Yeah, I know Will but the 1/4" bar is my first and only bar. :( I am going to ream when done but gotta get a true hole first. I gotta go for it. I got a whole bunch of things to do this weekend. I moved the lathe and mill so gotta relevel the lathe and level and tram the mill. That'll be first and then the sleeve job..... then whatever the family wants to do. :rolleyes: :)
 
Yeah, I know Will but the 1/4" bar is my first and only bar. :( I am going to ream when done but gotta get a true hole first. I gotta go for it. I got a whole bunch of things to do this weekend. I moved the lathe and mill so gotta relevel the lathe and level and tram the mill. That'll be first and then the sleeve job..... then whatever the family wants to do. :rolleyes: :)

Ah I see, my bad, I didn't pay attention to the 1/4" part. When I saw sleeve for a boring bar I automatically thought for the large boring bar holders for like a 3/4" or 1", etc boring bar.

Yup, go for it, use the center drill. Should be fine.

I'm a bit confused though, what is the sleeve for? Do you have any of the QCTP holders with the V groove on the bottom (like seen to the right in the background in the pic below)? For my smaller boring bars that's what I use & they have worked perfectly fine for me.

Here's a pic of my 1/4" boring bar. Only thing I had to do to mount that small of a boring bar was swap out the set screws for longer ones. (Edit: the stock length ones should still work).

20170526_163847.jpg
 
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Yes, I could try that. I will admit I'm afraid of breaking the carbide bar with those set screws. Believe it or not I've never done any boring before so it's all new to me. Is that a carbide bar, Will?
 
Yes, it's a carbide boring bar. I've never had an issue breaking or chipping, all but one of my boring bars are carbide. However I do use use flat point set screws with them. IIRC the stock set screws are just long enough to work with a 1/4" bar. With my China holders I always swap out the set screws for higher quality ones. I don't like the cup points digging into my tools so I use flat points on all my tool holders. You can also just grind down the cut points since most local hardware store don't sell flat points. Some tool holders come with dog points, those I don't mind if the set screws are decent quality.
 
Yes, I could try that. I will admit I'm afraid of breaking the carbide bar with those set screws. Believe it or not I've never done any boring before so it's all new to me. Is that a carbide bar, Will?
Don't worry you probably won't break it. Not unless you try to hog off a huge amount and get caught.
 
Do you have any split point drills , they usually hold dead center if you let it start the cut slowly.
 
I agree with Will. I would just use the center drill and then your pre-reamer drill without using a pilot drill. Then ream it and you'll be fine. I also agree that a reducing bushing is the way to go as it will reduce the potential for chatter when you go to use that bar. Since your bar is only 1/4", make the bushing at least as long as the boring bar tool holder itself.
 
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