DarZeelon

While I was looking at some 1/4" taps, I ran into an example that illustrates what suckers many hobby suppliers think we are...

The tap needed for the glow-plug thread in the head, is the 1/4"x32.

This size was, at the time, considered 'rare'...
One could easily find a 1/4"x20, a 1/4"x24, or a 1/4"x28 tap for pennies; yet the illusive 1/4"x32 size was nowhere to be found, or seemed very expensive...

Please take a look at [link=http://www.google.com/products?hl=en&rlz=1B3RNFA_enIL241IL243&q=thread+tap+1/4%22+32&um=1&ie=UTF-8&ei=YzFYSpbIFJbKnAOFr7zdCQ&sa=X&oi=product_result_group&ct=title&resnum=4]this Google page[/link].

As long as it is a *1/4"x32 tap*, you can get it from $1.90 ea., or a bit less in bulk (retail).

When it becomes a *glow-plug tap*, it's price suddenly leaps to $5.04 and more; over twice and a half the price, despite being the exact same work tool that the hobby supplier buys wholesale for the exact same price as the hardware supplier does...
The funny thing is that it is termed 'reasonably priced'...


It feels really good to be appreciated as a modeler...[:'(]

RCPAUL

My Feedback: (1)

I think Higley sells the tap.

Paul

Broken Wings

My Feedback: (20)

I hope I NEVER have to buy Glow Plug Taps in bulk.....

If you don't cross thread the glow plug in the cylinder head or "Ham fist" the plug so tight that you pull the threads out you can save the $1.90...

Just use your fingers to start the glow plug in the hole. Don't use a wrench untill the plug has found its way. A length of rubber tube pushed over the glow plug will help you start the plug in a cowl or difficult to get to cylinder head.

Simple...

pe reivers

I sometimes make my own combustion buttons, so I need one. I ordered mine as standard tool with my tools supplier. Good machibe taps, ground and hardened HSS steel are a little more expensive than 1.90 though. They last a life time.

Broken Wings

My Feedback: (20)

I've got an old South Bend 9" with lead screw gear box, power feed,etc. It was my fathers and I ran it when I was a kid. It's real hard for me to imagine going through life without a metal lathe.

What kind of Lathe do you use Pe?

DarZeelon

Quote:

ORIGINAL: Broken Wings

I hope I NEVER have to buy Glow Plug Taps in bulk.....

BW,


Using the 'in bulk' term, I meant five 'ham-fisted' hobbyist from one club, can chip in with just $1.65 each; and pay only once for shipping...

I don't even own such a tap, nor do I plan to ever buy one...


I had only one head that ever needed attention to the glow-plug thread... My HB.40PDP, nearly 29 years ago...

spaceworm

Here is a link to an industrial supplier: http://www.mcmaster.com/#hand-taps/=2p3v4z Price is USD 6.54 plus shipping and handling. In 53 years of messing with glow plug engines, I have never used a glow plug tap or needed one. Even in the Navy where "if it doesn't fit, use a bigger hammer" rethreading is a rare event. Treat your engine like a lady: gently, and with a tender touch. :-)

pe reivers

I have a 1954 model Myford 7 "table model"
Recently re-aligned the spindle bearings and slides, so it should be good for another 50 years.

w8ye

My Feedback: (16)

I bought a Higeley 1/4-32 tap four or five yrs ago and have only used it on other people's engines

blw

My Feedback: (3)

I've heard of needing one to try and undo damage done by a glow plug with bad threads.

Broken Wings

My Feedback: (20)

A Myford is a great Lathe, made in England I believe.

Motorboy

Every one can make own treading tap with a lathe as i did, see the pic...

Use drill rod as material, it is strong enough to treading in soft material such as in aluminium, brass..
Do not hardening the homemade treading tap or you will distort the tap for all perfect treading measure.

vicman

My Feedback: (10)

$2 taps are usually a recipe for poor results. Cheap in cheap out. I have used those cheaper taps but long ago. Once your day depends on good tools you don't think twice about that $5, in my case taps have run over $200 (much larger hole).

Another thought is that, from what I have seen of glow plug threads when someone is worried about the thread it's too late for an on size tap to do much good. Most of the time it requires a helicoil, at that point you are up in the $35 or more range, I don't remember what I paid when I bought mine. I've done repairs for the local hobby shops and a few RCU members over the years.

Broken Wings

My Feedback: (20)

I agree. You have to understand what "Class of Thread" you have to order the correct tap. The 1/4-32 UNEF (Unified Nantional Extra Fine) has two classes of fit 2A and 3A for an external thread.

A 1/4-20 has three classes of fit 1A, 2A and 3A

The "A" designation is used for a External Thread and the "B" designation is used for Internal threads as in 1B,2B, & 3B.

A tap will usually have a designator etched on the side after the size. "G" is for Ground Thread. "H" is the symbol for Above Basic Diameter. You may pick up an H6 tap that will cut oversize .0025 to .003" OVERSIZE to allow for coating of some type. "L" is basic dia. Minus .0005 so it cuts undersize.

Buying CHEAP tools is NOT a good Idea. Buying Cheap Cutting tools and passing them on to your fellow "Ham Fisted" club members is even worse.

DarZeelon

Quote:

ORIGINAL: Broken Wings

The ''A'' designation is used for a External Thread and the ''B'' designation is used for Internal threads as in 1B,2B, & 3B.

A tap will usually have a designator etched on the side after the size. ''G'' is for Ground Thread. ''H'' is the symbol for Above Basic Diameter. You may pick up an H6 tap that will cut oversize .0025 to .003'' OVERSIZE to allow for coating of some type. ''L'' is basic dia. Minus .0005 so it cuts undersize.

Buying CHEAP tools is NOT a good Idea. Buying Cheap Cutting tools and passing them on to your fellow ''Ham Fisted'' club members is even worse.

BW,


All the inexpensive taps in the page I linked, cut a 2B thread...

This includes the $1.90 taps, as well as those called 'glow-plug taps'... They are the same item, sold in a more fancy package, with a name more appealing to glow engine users...


I do agree with Vic that high-market taps that run for about $20-30 a piece, will probably last much longer; for sure if used by a ham-fisted person...


But this ain't the case... The hobby outlets are selling us $1.90 taps for $5-9; not the $20-30, better quality ones.

captinjohn

A interesting side note...look at the threads on anything with a 50x viewer. Poor threads look like they are ripped in. I think the better threads are gound when formed. There sure is a big difference!!! Even on the point of a small fish hook. Yup I did work (for a couple of years) in a recieveing inspection job....its no fun for sure. Capt,n[:-]

Broken Wings

My Feedback: (20)

Have you ever used a tap? There is a huge difference in the way that cutting tools perform. I'll pay the extra couple bucks for a tool that works.

Thanks anyway.

Mr. Mugen

http://www3.towerhobbies.com/cgi-bin...?&I=LXFX27&P=Z

Most people won't pay 20-30 bucks for a tool to fix a 20 dollar part either. If they used it everyday it would be different but for something to clink around in a field box until needed seems foolish. The beating a good tap would take would kill it before it was used. This is assuming the ham fisted fellow treats everything the same. Of course a good tap comes in a nice hard sided sleeve....usually with rubber ends too. I never bought a cheap tool I liked. Only quality stuff for myself, even on those once in a blue moon use tools.

Kevin

JPMacG

My Feedback: (2)

I expect Harry Higley does not manufacture taps. They just buy them from a machine supplier, mark them up, and sell them to hobby shops, who mark them up further. The same goes for most non hobby-specific stuff we buy. The little 2 oz bottles of after run oil in the LHS are probably repackaged ATF, marked up 1000 percent. Same for the the bags of machine screws and nuts for sale at the LHS at 10 X their cost from McMaster Carr.

DarZeelon

Quote:

ORIGINAL: Broken Wings

Have you ever used a tap? There is a huge difference in the way that cutting tools perform. I'll pay the extra couple bucks for a tool that works.

I have, BW.

In fact, I did it in an OS.61FSR head and I did it in a machine shop, with a Bridgeport lathe.


The user of this engine had badly cross-threaded his head...

The machinist I knew (a girlfriend's father...) bored out the whole middle of the combustion chamber, threaded it a larger coarse size and screwed in a brass insert, after cooling it in liquid nitrogen...
He then held the head in the four-jaw chuck, 'blended' the insert into the combustion chamber and machined it flat on the top-side.

Still held in the chuck; I drilled a hole dead-center in the brass insert; I believe is was either 7/32", or maybe 15/64" drill bit...

Then I held a 1/4"x32 tap (an expensive one, I believe; he was an expert in gas/hydraulic tubing connections) in the drill chuck in the dead-center and fully threaded the hole... The outer side was chamfered with a 9 mm drill and the inner side just smoothed.

The glow-plug was a perfect fit.

I did thread a few more holes, in large parts, with a hand held tap handle... Those were coarser threads, however.

I never broke a tap.

jeffie8696

Won't a cheap tap work for thread chasing which is all you are doing if the threads are just a little boogered up? I am always looking for an inexpensive alternative to everything since I am incredibly poor.

Broken Wings

My Feedback: (20)

I'd liked to have seen that Bridgeport Lathe.

Broken Wings

My Feedback: (20)

Just buy the K&S tap from tower....There $7 bucks. It's a four flute HSS hand tap made for just that. Use the $10 off coupon 592PH

jeffie8696

I have run hundreds of engines and never had the use for one. I did manage to strip the threads out of one engine after testing every plug combination I could come up with. I probably had the plug in and out about 100 times. LOL

Campgems

Dar, I get my taps from an industrial tool supplyer and their price is $8.22 for the 1/4-32 tap. Iknow it quality and was happy to pay the price, but I'll keep your list of suppliers in case I need another. This is quite a spread in prices. Along as they areHSS Ground threads, I would think that they would be nearequal in quaility. Sometaps, IEthe Craftsman taps are not very good, not that you'll find a 1/4-32 tap from them, They cut a fuzzy thread andalthough I've got a set, I won't use themfor any thing other than maybe cleaning up a thread, but even then they fall short.Their dies are not much better, but will do in a pinch.

Don