A wee bit of metal working got done...

[steven c newman]

today. I had bought a 1/4" slab to replace the 1/2" thick one on my Stanley 358 mitrebox. I still had some leftover 1/8" x 1/2" flat bar stock, from the 3' I bought to go between the tops of the saw guides...had 22" left over. Picked a couple hex head bolts.....shank was just under 1/2" diameter. I could hacksaw the heads off. I could drill a hole near each end of the flat bar. Tap some threads to match the bolts. Once each bolt was threaded through and tightened down, I could hacksaw off the excess threads....
IMAG0001.jpgIMAG0002.jpg
I had, I thought, cut the second one long enough....missed it by thank much. No biggie. Grinder to round some edges. Smoothed the rough stuff down with the grinder. Underside is flat, and smooth, should slide nicely in the dados.

I did find out a lot of my metal-working drill bits are a bit on the dull side.....might as well just get a few new ones, just to match the taps I have.

Now, maybe figure out how to fabricate a "tree" for the stop rods to use? Might need to buy a new rod or two, as well.

[Jim Koepke]

I did find out a lot of my metal-working drill bits are a bit on the dull side.....might as well just get a few new ones, just to match the taps I have.

Drill bits are fairly easy to sharpen. A Drill Doctor starts out at about $50. I do pretty good freehand.

jtk

[Patrick Chase]

I did find out a lot of my metal-working drill bits are a bit on the dull side.....might as well just get a few new ones, just to match the taps I have.

I like the Chicago-Latrobe 550s (standard flute, not ASP) FWIW. It's a good solid M42 Cobalt bit with 135 deg split-point tip. Not cheap (esp if you need a full set with wire gauge bits) and they'll break if you abuse them, but worth every penny IMO. I also have some 150ASPs (HSS, thick flute) for stuff where breakage is a concern.

Can you sharpen your old bits? Like Jim I've had OK luck with Drill Doctor (though their splitting solution creates a very steep splitting face on smaller-diameter bits, which thins the flutes too much)

[steven c newman]

Used to be able to resharpen all the drill bits.....grinder no longer equipped to grind new drill tips. mainly due to the rest being changed to allow grinding bevels on chisels and plane irons. May give a couple a try tomorrow.

Flat bar was from Lowes, what they called "weld" steel. Supposed to be easier to work with....meh.

I don't do a whole lot of metal working, other than tap & die work. I would be looking for the sizes used with the taps I had... non-metric ones. part of the reason I picked that empty drill index over the weekend. I can refill it as I get a few drill bits. Label them for which ever tap it goes with.....like a "7" to go with the 1/4" taps....

[Jim Koepke]

I would be looking for the sizes used with the taps I had... non-metric ones. part of the reason I picked that empty drill index over the weekend. I can refill it as I get a few drill bits. Label them for which ever tap it goes with.....like a "7" to go with the 1/4" taps....

Most of the metal drill indexes I have seen list the drill for tap size on the front row of bits. Have you checked yours?

jtk

[Patrick Chase]

I don't do a whole lot of metal working, other than tap & die work. I would be looking for the sizes used with the taps I had... non-metric ones. part of the reason I picked that empty drill index over the weekend. I can refill it as I get a few drill bits. Label them for which ever tap it goes with.....like a "7" to go with the 1/4" taps....

That's exactly how I ended up with a full set of 550s including wire gauges.

Being nitpicky, a #7 corresponds to ~75% thread depth for 1/4-20 (and wouldn't be workable at all for 1/4-28). I think you'd want a bigger bit than that in steel, though I'm sure George will be along to straighten me out momentarily. IIRC I used 60% the last time I tapped some annealed O1...

EDIT: Just checked, and I use a #4 (60%) for 1/4-20 in steel. I know because I had to replace one not so long ago.

[steven c newman]

Been awhile, trying to remember if it is a 7/16" bit for a 1/4"x20....

We used to use a self-drilling, self-tapping screw when I worked in construction......it would cut threads that a 1/4" x 20 fit exactly...made hanging doors in steel frames very easy to do. It used a 5/16'' hex driver. Those type of drivers were almost like gold, and the longer one was on a jobsite, the scarcer those bits would get. APEX used to make a good one, when you could find them...

There is a chart out there, somewhere, showing which drill size went to which tap size. Had one, somewhere.....been a long time since I used it.

[steven c newman]

Will have to clean it up first. I'll take a look tomorrow when I can...tap I used today was a 3/8 x 16 nc I have to be careful which ones I pick out of the tray, as there are a few listed as a NPT style tap ( National PIPE thread) not much works with those...

edit: found the drill index......3/8" x 16 is the tap, I looked up the 3/8" bit slot......all that was listed is the drills diameter..... 0.375" The 1/4" slot is a 0.250....looks like I'll google up a chart, sometime..

[Jim Koepke]

Been awhile, trying to remember if it is a 7/16" bit for a 1/4"x20....

Been awhile since you have run through the fractions? A 1/4-20 tap would fall through a 7/16" hole. Maybe a 7/32" hole... Well at least you got the 7 part.

I have a few charts, they are all over the internet. They are also in the last pages of a lot of tool and other catalogs.

Starrett Catalog No. 32 page 555 is where mine comes from. Not sure that still exists. There are a lot of catalogs listed here and they will send you copies free:

http://www.starrett.com/catalogs/pdf...l-line-catalog

If it wasn't a problem with TOS I would just post a pdf of the drill page.

For 1/4-20 threads they have this:


size - 1/4" UNC+ 20
Outside Dia .2500"
Pitch Dia .2175"
Root Dia .1850"
Tap Drill ~75% full thread 7
Decimal Equiv of tap drill .2010

7/32 = .2187

jtk

[John Ziebron]

My very old Craftsman set has the drill sizes required listed on the inside of the case cover. Also, as Jim mentioned, the pilot drill size required is shown on the tap itself. There are many charts out there. Here's a basic one that shows SAE and Metric sizes: http://www.lincolnmachine.com/tap_drill_chart.html.

[Jim Koepke]

The current Starrett catalog is #33. The tap drill sizes are listed on page 547.

This is the link for the catalog download:

https://starrett.egnyte.com/h-s/20140804/yokfALfWAG

You have to click the Download button on that page.

jtk

[steven c newman]

Thank you!

Suppose I could have looked up a chart @ NewmanTool Co. site as well....

Ok, these were for the stock guides that hold a board in place on the 358 mitrebox. After that, need to redo the wood deck. Add the dados for these guides to slide in and out in.

Next big metal working project would be to build a "tree". These have a stand of sorts, to hold the stop rods. It would have two places for the rods to go through, and threaded holes for thumbscrews to lock the rods in place. Then you can set things to length of cut, and keep cutting boards to that length. I had two of the rods, and the collar to join them with.....might go with new rods, as the OEM ones were a bit pitted.

As for buying a "tree" for this saw? Good luck, I'd have been luck winning the LOTTO.....

[Patrick Chase]

For 1/4-20 threads they have this:


size - 1/4" UNC+ 20
Outside Dia .2500"
Pitch Dia .2175"
Root Dia .1850"
Tap Drill ~75% full thread 7
Decimal Equiv of tap drill .2010

7/32 = .2187

jtk

Yeah, there's no doubt that a #7 corresponds to 75% threads on 1/4-20. The thing I was questioning is whether that depth is desirable in this specific case. I learned to aim for more like 60% in steel unless the material is really thin, but a quick search reveals a huge range of opinions.

Steven, if your taps aren't breaking and the force is manageable then there's no reason to change.

[Robert McNaull]

I worked in a shop one summer that had a $2k professional grade sharpener. Used it for a while and learned what sharp should look like on a drill bit. Went to engineering grad school and our shop had no sharp bits that were accessible to students. Good ones were locked up for the shop supervisor. So I learned to free hand sharpen and based my methods to mimick what the professional system would produce. Pretty good at it now, no longer a student, but still wor in the same shop a few times a year and take any drill bit I use to the grinder before I even bother using it. All about setting a solid base slope on the point that meets in the middle then make a secondary bevel to reduce the aggressiveness and split the point. Just glad the tooling grinder isn't locked up.

Bob

[John K Jordan]

....might as well just get a few new ones, just to match the taps I have.

Steven, for the sizes I use the most (like 1/4-20) I started buying the little sets with a tap and the right drill bit in the same package. This saves looking through my numbered sets for a #7 and saves wearing them out.

I do prefer screw machine bits for general metal work - they are shorter so they don't flex as much.

If you do a lot of tapping, this thing is quite useful: hand tapping machine that keeps the bit perfectly vertical and allows easy control. My 4-year-old grandson used it to tap some holes in 1/4" steel. Grizzly hand tapping machine:
https://www.amazon.com/gp/product/B0000DCZ9V

JKJ