Adding Setscrews to Stanchion Bases

[mbd]

Hi guys,

I'd like to modify my original stanchion bases by adding 2 setscrews each so I can remove the stanchions and lifeilines without having to remove the bases for winter tarping. They are currently all off the boat and in the basement, so now is the time to do it.

Is it even possible without a drill press? I assume I'll need a special drill bit for drilling stainless? Should I drill them opposite each other? Do I need more than one setscrew for each stanchion? How about just tapping the existing hole that goes all the way through the base and tube, then just add another hole to the base that doesn't penetrate the tubing? Would this be more secure than drilling 2 hole into the tubing? And - how do you tap the new holes?

Any "how to's", advice, and ideas welcome.

[Commander 147]

Mike

It's been so long since I took my stanchions off that I forgot what the base looks like but from your post I think I can tell you what I would do.

If there is a through hole now I would use that to make my set screw locations. First find the right sized S.S. set screw by finding one that the "drill size" for the tap is just slightly larger than the existing holes. All taps have a specific drill size that should be used with them. I would start by finding a source for S.S. set screws like theses guys... http://www.boltdepot.com/Set_screws.aspx?nv=l and then find the set screw that is a little larger than the existing hole.

To drill the base you can do it with a hand held drill just set your drill to turn very slowly and apply firm pressure. A squirt of oil once in a while will help. Heat is what destroys drill bits when you attempt to drill stainless. So turning the bit slow with firm pressure and oil lubricant will work much better than trying to drill to fast and burning up the bit.

Once the holes are drilled I would put the tap in a hand held holder and turn the tap in slowly by hand. You can feel when things are binding up and when you feel that stop and back the tap out again. Then shoot some oil in and start again. It's a slow process but can be done more easily if you don't rush it.

The advantage of going in the original holes in addition to not having to start the hole from scratch is that the set screw will turn part way into the stanchion through hole and lock it in place.

That's my take but your mileage may vary :-)

[ebb]

ebbdon'tknowitall here,
but like you, probably, I've ruined a bunch of bits making holes in stainless steel..
A google search shows that you and I aren't the only ones.

Not sure what material your stanchion bases are. If they are bronze, there's no problem.
If they are s.s. there is a problem.

First of all, what is that hole that already exists in the stanchion base that goes all the way through?

If it goes all the way through the stanchion-base wall, in and out the other side, why not use a clevis pin - or hero cotter pin. A no thread deal like that would be much prefered! Actually it's a great idea!!! Even #8 or #10 machine screws with a nyloc nuts would get away from nasty cotterpin tails.

If you insist on going the set screw route, here are some resources:
First go to McMasterCarr (pg3072) to see what kind of set screw you might want. For instance, you can go with a cup point that you drive in and will engage the tube without dimpling because the cup has a sharp edge. But you might like a cone point, for which you would dimple the tube so that the cone insets slightly. This has better holding. If you have to enlarge and re tap the stanchion base for a larger set screw, you can chose a set screw with an extended smaller tip that could engage the tube with a smaller or the original hole in it.

If you have to drill a hole in the tube, you have a challange. Sailrite sells a $49 "drill steady" that clamps around 7/8s-1" tube that allows you to drill a 1/8" inch hole. You could probably make the hole larger, if wanted, with a hand drill. Any drilling in stainless tube requires a brand new or newly sharpened bit. Usually three or four. Drilling holes in thin stainless is different then sheet or plate - because of it's structure and thin-ness. Of course it's the type of stainless, 304, 316 - thickness of wall - but also how the tube was made.

You might also find a larger tube drilling jig made out of two opposing right angle pieces of aluminum that you clamp around the work. It might be around the same $50 whack. It could be used, maybe, to get holes in stainless stanchion bases since they are fabricated usually with tube. If cast stainless bases, no experience here. But to drill em you probably have to immobilized em and use a drill press.

Imco the set holes in the stanchion base should be in the fore-n-aft position, parallel to the toerail, so that pushing or pulling on the tube won't tear or perhaps break the set screw in the base - which might happen if the screw was on the 'cabin' side of the stanchion.

Here is an exquisite DRILL & TAP CHART from steven henderson's cutting edge designs (have to give him full credit!) www.shender4.com/thread_chart.htm.
Here you will see clearly that to drill for a 10-24 or 10-32 or 1/4-28 set screw you need the correct number drill, and a tap of the correct size to thread the hole.

www.icscuttingtools.com is probably the only website you possibly get cobalt bits for s.s. in size
25-20 or 21-18 for the #10 set screw - 1/4-28 set screw wants number 3 or 1 - depending on the alloy of the base and depth of thread.
Had a preliminary conversation by phone with ICS about adding number and letter bits to a sweet 40pc HSS hex die and tap set found on their site... for a bunch of $$. Imco if taps & dies are going to last for any time on stainless they have to be HSS. Same for using cobalt bits.
I don't know if ICS will sell a specific die or tap, die or tap handle, and set of bits - but it may well be worth a try. It seems to be a generational mom-n-pop outfit with a knowledgable person on the phone! The site is beautifully set up, it's a gas to cruise!


Drilling tube, I'd make a jig from a thick piece of wood that has the OD of the tube size drilled thru it. Then cut the piece in half to clamp it around the tube. This ought the keep the tube from crushing - and with a predrilled hole of the correct size will make a steady for drilling. Depth of wood around hole would make it easier to control the variable speed drill. Friction here would be helpful (but also heat up the bi!)
A bench press would allow the drill speed to be at DEAD SLOW. With a NEW bit. You have to feel for the amount of pressure needed, and for the sudden let-go when you drill thru. Right befor you drill thru is where a bit catches on thin steel still attached to the unfinished hole - and snap goes the bit. You have to keep raising the bit out of the block to clear chips. And squirt in coolant.
Also important is not letting ANY HEAT build up. It'll harden the steel and dull the bit immediately. This will probably happen no matter what you do - have extra bits. We see various liquids used for cooling and lube. Imco cooling is way more necessary than lube: cutting oil, WD-40, condensed milk out of the can.
For COOLING especially with cobalt: I've been lucky with plenty of denatured alcohol dispensed with a restaurant vinegar bottle, or just plain water.

All the way thru base and tube with a pin is the way to go! No threads. Easy to remove.
__________________________________________________ __________________________________________________ __________
NO DOUBT for a short job HSS split point drill bits should surfice.

Sorry about the load here. And I began the post not knowing that Jerry was going to get posted befor me.
So my thoughts are an effort to respond to Mike's post. Sorry for any confusion.

[bill@ariel231]

All of Jerry and Ebb's points are well taken, oil is always a good idea drilling thru stainless.

On the boat Alyce and I race (A friend's Frers 40) the stanchion bases are thru drilled and fastend with an 8-32 machine screw. No problems with these in years of inshore and offshore racing.

For A-231 I followed a similar path but replaced the set-screws with 8/32 machine screws that engage the stanchion pipes (these are drilled thru on just one side, at the point that the set-screw formerly bore against the stanchion).

No doubt thru bolting is stronger but i did not need to modify the stanchion bases. It is stronger than set screws (I can pull on the lifeline up without worry about removing the stanchion from the stanchion base).

Offshore thru bolting is a good idea. In-shore just about anything goes, but thru drilling one side of the stanchion and leaving the stanchion base un-modified worked for me (and they are still easy to remove for the winter cover).

cheers,
Bill@ariel231

[mbd]

Thanks for the feedback guys. I like the idea of machine screws - seems easier to deal with and simpler to remove and replace when necessary.

[ebb]

RELTON (NEW) RAPID TAP for as long as I can remmber has always been near the drill press. You've seen it: it's a small (4oz) yellow can with red printing. The plastic nozzle aways was chewed up from getting too close to turning bits. It used to be primarily composed of 1,1,1 trichloroethane, a chloronated hydrocarbon solvent. The 'new' means it is now reformulated and is... oily.

There are waterborne synthetic tapping fluids that leave no oily residue on the work.
SAFETAP PLUS and SAFETAP ULTIMA are clean and biodegradable.
RE-LI-ON is a do-all fluid that is not waterbased and is 'engineered for stainless and safe for aluminum.' Also comes in a 4oz plastic bottle.*

I've been trying to find a liguid that can be used for cooling and lubing s.s. that can be cleaned up without using solvents. Haven't found it.
For a job like the s.s. stanchion bases that can be easily de-oiled Rapid-Tap would be my choice.
(For drilling holes in the old mast I'm going with denatured alcohol as coolant-sans-lube to avoid contaminating the metal and using clean-up solvents (and contaminating the metal) any more than necessary. It would great to SafeTap but
I'm skeptical of these tapping fluids because they are made with emulsified oils and paraffins that might stick around on the metal long after cleaning.)

I've read (and maybe experienced) that center punching to locate the drill bit on stainless can work-harden the dimple! Like maybe with an extra whack! That would make it tough on the first small bit in a series of enlarging bit holes. It'll only takes a couple seconds of skidding the bit in a depression without doing any cutting to work-harden the attempted hole. Done it!
And tapping such a hole would be hard to nearly impossible. And breaking the tap in the hole will ruin your whole day.

Imco Rapid-Tap (in a metal can) is the only conveniently packaged all-purpose cut & tap lube oil we can keep around the boat or in bosun's stores. That's the one by default. Cannot be used on plastic. It requires a companion degreaser, maybe there's an all purpose cirtus product for that.

*RE-LI-ON is quote:
"Hydrocarbon Mixture - Ingredients: Severely Hydro treated Naphthenic Distillate, Chlorinated Paraffin, Chlorinated Fatty Acid" That's what it says!
maybe more sticky/slimy than oily.


What's that? Machine screw keepers for the stanchion bases? Ah h h, too easy!
Mike, show us a pic here how it's done!

[mbd]

Mike, show us a pic here how it's done!

But that would require me to actually DO something!

So I won't need special diamond tipped bits or anything like that?

[Ariel 109]

Mike,

You might find it quite easy to drill through the stainless tube, slow speed and a little oil. I like those pilot point drill bits Dewalt sells at Home Depot, they perform well. One of the dirty secrets of the trade is to use a slightly over-sized bit then what is called for when drilling a tap hole. If you do break a tap, easy to do, you can remove the tap fragment with a nail set and hammer.

Ben

[mbd]

One of the dirty secrets of the trade is to use a slightly over-sized bit then what is called for when drilling a tap hole.

Great tips - thank Ben. But can you clarify this statement? Wouldn't the tap need a SMALLER hole?

Jerry - I'm looking at the Drill and Tap chart you posted. Specifically the 8-32 as Bill used. It says I need a "Tap Drill" size of 27? Also a "Clearance hole" drill size of either 18 or 16
What does the drill size mean? Will it be obvious when I go to purchase them? And how does Ben's suggestion of a "slightly over-sized" bit work into this?

Thanks again for all the helpful info guys!

[ebb]

http://www.shender4.com/thread_chart.htm
Mike, that drill & tap chart takes the guess and by god out of the picture.

Bits for tapping can be found in those 115pc sets in long metal cases.
They have full sets of fractionals by 64ths, wire size and number bits.
Getting the correct single bit at your local hardware probably won't happen

Short of buying a $150 set of bits. I might call ICS and see if they can help.


The explicit henderson chart can give you the nearest fractional bit to a number bit like:
43=3/32. 36=7/64. 29=9/64. 25 or 21=5/32. 16=11/64. 7=13/64. 3=7/32.
If you have no access to wire and number sizes.

Using the chart you will see in the "CLEARANCE HOLE drill" column, CLOSE FIT. FREE FIT.
That gives you the drill bit size that would clear all the thread out of the hole of the size you are considering.
Therefor you will be able to choose a SMALLER bit, MAYBE a more common size to make your tapping hole with.
The chart gives you bottom line on your choices.

The "Clearance Hole Drills" are not diameters used for tapping.* They are for slip fitting the screws through your work.
Henderson gives us a tight fit and a loose fit. Like the holes in the stanchion base for fastening to the deck.
(* altho there will be a few crossovers, EG: The recommended Close fit Clearance hole for a #6MS is Number bit 27
which is also the recommended tapping bit size for the 8-32MS.)

Threading/tapping STAINLESS uses a bigger hole for the same MS than softer material like aluminum or bronze or plastic.
The chart calls it a 50% thread. You might find a bit that will still give you a hole
that gives you a 45, 40, 30% thread.
It'll be easier to tap. But it is off the chart.

Obviously the tap has to be for the machine screw size you are using.

The henderson chart also gives us a reference in decimal equivalents for the major and minor diameters of the thread on the machine screw
that may be useful in choosing a non-recommended drill bit for the tapping hole.
The 4 digit decimal equivalents imco make it easy to compare differences and closenesses of fractionals, Wire size and Number sizes.
If you have some metric drill bits, the decimal equivilents in the chart might get you closer to a better alternative tapping size.

There is much less leeway for alternatives in hard stainless.
__________________________________________________ __________________________________________________ _____________
COBALT BITS come in three grades: chinese, M35, M42. A long box set of M42 (115pc 135degree split-tip) will cost $300/400. Most cobalt sets are M35. And are correspondingly cheaper. Both are uncoated HSS 5% or 8% cobalt alloy - which makes them stay hard at high temps and more brittle.
I have a 29pc cobalt in the same ole St.Paul case my carbon bits 40 years ago came in. This set came from Northern Tool - they are stamped on each bit M42 USA. Now $99 - ask if they are US. I bought some Irwin/Hanson cobalt singles at the local, and they dulled on me immediately! Bought some Bosch and they have lasted. C. bits are not coated and can be sharpened and will last if you scored real ones. Titanium is a coating and after the first sharpening they are regular HSS, which may not be the worst bit. Cobalt are heat-treated as a last step in making and have a recognizable thin gold color. It oxidizes over time into a darker shade but doesn't change the cobaltness of the bit. I might spring for a Harbor Freight $1 a bit long box because H.F. is working hard to build their image as a place to find decent tools. Somebody needs to do a comparison test of what's available. McMastercarr does not say what grade their cobalt sets are (29pc $198.14 ---115pc $528.65). But you can order singles to replace broken ones in yer bargain sets.

[Ariel 109]

Ebb pretty much covered the over-size tap drill for threading hard materials. It's just if you go to the hardware store and get a packaged 8-32 drill and tap set you'll find that the drill included is for tapping soft materials not stainless. I would recommend again the pilot-point bits. They cut very clean holes, especially when you cut through the material to the back side of the hole, which can be a problem. Low speed and some lubrication will prevent you from burning up your drill bits. You can burn up a cobalt drill bit almost as fast as a HSS bit with a fast drill speed.

[ebb]

Ben,

Of course ebb didn't know about these...
They seem to be a DEWALT patent. google images yellow wallpaper! Here's some poop on the subject.
A 29pc fractional set in yellow plastic box (DW1969) goes for $79.99 at Northern Tool, $56.95 at Ace. Country of origin Germany.
These are NOT cobalt or they would say so. Credible reviewers say the DW1969 pilot points self-feed & heat up in wood and chew up exists in wood and 'splinter' fiberglass. One metal shop says they last well but burn out with not enough pressure - work well in a drillpress - also grab as they do in wood & frp. Another reviewer says they break in industrial steel studs w/ a high speed portable. WHY is the bit alloy secret? Never mentioned in the Dewalt hype or even asked about by the 'reviewers'. So strange.
McMasterCarr doesn't look like they have any pilot points. Brad point bits aren't for metal.

Grainger has a COBALT PILOT POINT DEWALT 29pc (DW1269) in a dark gray box for $151.75 (find them cheaper on the net) - this set SAYS cobalt. M35 or M42? Country of origin China. I'd go with this set at the right price. They are available in singles and say cobalt. No user reviews.
DeWalt also has a 29pc set of regular point cobalt bits in a black box (DD4069).
All sets look cobalt with the 'gold ferrous oxide' finish that usually is a cobalt ID thing. It isn't a keep-sharp coating.
The yellow box DeWalt bits are probably HSS, but the description in Granger or the Dewalt home page doesn't say. It could be M2, no cobalt.

Grainger also shows a generic WESTWARD brand of cobalt pilot point bits which say M35 - $118.15 for the 29pc. (And a HSS set of M2 for $58.)
I'd guess the DEWALT & Westward cobalt bits are made in the same chinese factory. So if the Westward 29pc pilots are M35 then it could be assumed so the name brand. Grainger sells the pilot points individually. BUT ASK WHICH DEWALT PILOT POINTS THEY ARE...cobalt or yellow box.


What this 'pilot-point' design does is put a small hole boring bit on the end of the hole size bit. Something like that. Looking at close ups, we might use a diamond file to touch up the bit, BUT we can't put it into the DrillDoctor to resharpen. Which normally is the reason to have UNCOATED cobalt.
So it may be better to buy bits individually.
And make up a set of taps and dies and bits dedicated for the boat - including applicable pilot points if you like em.
I'm leaning that way because McMasterCarr has a lucrative relationship with me, I'll cobalt with them. The full range of 135 degree split tip wire, number & fractionals are available individually, I believe. AND any full set of taps, dies & drills from them is way too expensive & will include pcs never used.
(M2, M7, M35, M42 - M stands for molybdenum in HSS. HSS is a high temperature tool steel alloy type that contains Molybdenum to aid flexibility. M35 & M42 have cobalt added: 5% & 8%, which allows even higher heat resistance befor losing temper - but makes the alloys more brittle.)
Have to find out why McMC doesn't use this grading system in scoring their HSS and cobalts.. Annoying.

FRACTIONAL BITS FOR TAPS
Make a decimal equivalent chart that translates fractionals to see how close 1/64 range bits come to the spec in the chart for the 50% stainless steel tap drill designation. Aluminum is 75%. Cool if all tapping could be done using common fractional bits from the DeWalt 29pc or a cobalt set.
A couple examples:
Thread/Screw Chart Tap drill(27) for 8-32 (in s.s.) is .1440. (Major Diameter of a #8 = .1640) Closest fractional is a 5/32 bit = .1563.
Tap drill(20) for 10-24 is .1610. (Major D = .1900) 11/64 = .1719.
Tap Drill(7/32) for 1/4-20 is .2188. (Major D = .2500) 7/32 = .2186(!)
Tap Drill(1) for 1/4-28 is .2280. (Major D = .2500) 15/64 = .2344.
What's the % of thread here? Recommended for stainless is 50% and the master chart is set up for that. Using these fractional bits as suggested seem to show larger holes and less percent thread. Is 40% or 30% enough thread to be Ben-able? Who remembers their algebra?
Is it OK to use larger than recommended fractional bit diameters for tapping?
Haven't seen any other forum talk about this! On this site we always on the cutting edge. Maybe Ben has the source?

DEWALT literature sez they came up with these pilot point bits to use in portable drills. Makes this set a good choice for the bosun's locker....Maybe.
Do they work in thick s.s. (like a stanchion base)
or are they mostly for thin stuff (like the stanchion tube)??
Guess that any hand drilled hole will measure larger than the same hole done on a drill press. Need a steady hand & a good eye for tapping.
__________________________________________________ __________________________________________________ _____________
When I spoke with ICS Cutting Tools, asked why they didn't have companion sets of the rediculous wire, number & fractional drills that are married to tap & die sets? "OH! THAT's a good idea," she said. So why hasn't somebody offered this, especially for the popular 40pc sets? Seems like a no-brainer.
Anybody know of any venture capital? Have an idea for an ultra/premium/deluxe tap-die-drill+accessories softpak kit aimed at the marine market!

Wouldn't it be nice to zip open a case and have the compleat tap&die kabootle right in your lap! The whole array of bits-taps-dies with spares and ALL accessories!