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View Full Version : Ba$#~úd day, ba<*":d job.



John Stevenson
01-06-2014, 06:40 PM
Fork truck motors often have a splined shaft that either drives hydraulic pumps or in the case of the older ones, direct into the gearbox.

These are integral with the shaft and either hardened on the teeth or toughened. The shaft cannot be pressed out and replaced without a full rewind on DC motors because the rotor part and the comm are separate.

Normal procedure is to cut the damaged spline off, bore the shaft out and stub with a new splined piece.

So what can go wrong ?

Answer is, at some time in the past this armature had been done before and a new stub pressed in and pinned. However some gorger had secured it with four 8mm [ 5/16" ] hardened dowel pins in a double cross formation, then welded then in.

http://www.stevenson-engineers.co.uk/files/spline1.jpg

Worn spline dropped back on the Armature after being cut off [ forgot to get a pic before hand but didn't know at this point the pins were hardened. ]

http://www.stevenson-engineers.co.uk/files/spline2.jpg

You can see where the pins were fitted and welded in.

That little cock up by whoever ? cost me about two hours extra, 3 triangular boring tips, 4 solid carbide end mills [ used but used as drills ]
Much cursing and swearing and forced me to go down the pub for a pie and a pint.

Stub not finally fitted at this point as it has to go across the road to the hardening shop but should get it back later tomorrow with a bit of luck.

wierdscience
01-06-2014, 07:24 PM
Looks good as always John,what did you use for a cutter to generate the spline?Involute gear cutter or form tool?

lakeside53
01-06-2014, 07:30 PM
Thought you'd retired? lol

CarlByrns
01-06-2014, 07:41 PM
<snip>at some time in the past this armature had been done before and a new stub pressed in and pinned. However some gorger had secured it with four 8mm [ 5/16" ] hardened dowel pins in a double cross formation, then welded then in.


You just know as the guy was whacking those dowel pins in (with a 'eavy 'eaded 'ammer) he was thinking "What a great job I'm doing. This outta last forever. I'll weld 'em just to be sure."

Arthur.Marks
01-06-2014, 07:54 PM
John, may I have a clarification on the term "toughened?" I mean, if it isn't hardened then what is it... forged? Maybe the term refers to case hardened (as opposed to through-hardened), but wouldn't that still be "hardened?" Perhaps it's an English colloquialism?

John Stevenson
01-06-2014, 07:57 PM
Weird,
Hobbed them with a spline hob 10/20DP That's a modified 10DP hob that only cuts 1/2 as deep hence the 20 bit
Pressure angle is 30 degrees on splines as a rule I bought some spline hobs as they came up on Ebay for just this purpose

Lakeside,
The ba$t@rds won't let me retire, they still come knocking on the door

Arthur,
Toughened as in using steel that has been pre heat treated, Don't know what you numbers are but we can buy EN24 steel in different states of heat treatment There is plain EN24, EN24M which is easily machined and EN24T which machines nice with tipped tooling and right speeds / feeds and coolant
Get it wrong and it's like witches tits

Edwin Dirnbeck
01-06-2014, 08:14 PM
Spline drives are usually bulletproof . What is causing this to fail .

Arthur.Marks
01-06-2014, 08:22 PM
Ah - many thanks for the explanation. I understand now. That material in the US is often called "pre-hard" -- which is just as confusing, I imagine, as an identifier. Most common is 4140PH, which is a medium-carbon steel with a hardness in the 32HRC (Rockwell C) range.

Mark Rand
01-06-2014, 08:25 PM
That's a direct equivalent to 4340PH for our colonial cousins. Lovely stuff in that condition. Turns like glued together spaghetti when soft and like rock when hard.


Did they pay enough to cover the work John?

flutedchamber
01-06-2014, 09:57 PM
Spline drives are usually bulletproof . What is causing this to fail .

Possibly the female mate to it is worn and putting all the torque on the tops of the splines.

john hobdeclipe
01-06-2014, 09:58 PM
My Dear Friend John,

In your second picture I can't help but see a bottle of some sort of "solvent" just in front of the blue handled hex wrenches.

What is it? Does it help? Or is it indeed a lubricant instead?

Just curious,

Your Friend John

MTNGUN
01-07-2014, 12:01 AM
I never cease to be impressed with your efficiency, Sir John. If I attempted something like that it would take me a week or two. :D

How will your stub be attached ?

gcude
01-07-2014, 12:39 AM
My Dear Friend John,

In your second picture I can't help but see a bottle of some sort of "solvent" just in front of the blue handled hex wrenches.

What is it? Does it help? Or is it indeed a lubricant instead?

Just curious,

Your Friend John

When John said, "Much cursing and swearing and forced me to go down the pub for a pie and a pint.", he was just being modest as usual. Looks like the repair may have taken more than a pint this time around.

JRouche
01-07-2014, 01:20 AM
You can see where the pins were fitted and welded in.

That little cock up by whoever ? cost me about two hours extra, 3 triangular boring tips, 4 solid carbide end mills [ used but used as drills ]
Much cursing and swearing and forced me to go down the pub for a pie and a pint.



Ouch! So when you started hearing the "crunching sound" you had to be thinking "this job is gonna be a bad one". Bummer.

Curious? When you knew you were hitting something hard did you change your speed and or feed or go at it with the same drilling and boring plan?

You always amaze me with the work you do. Reminds my of my dear departed friend Del who owned a job shop. Everything and anything landed on his table. Never shied away from any job. Most of his mainstay was pumps and the like. Enjoy the pie and pint!!! JR

jhe.1973
01-07-2014, 02:36 AM
Much cursing and swearing and forced me to go down the pub for a pie and a pint.



That's what made doing the job possible - it works in my shop too! :D

Nice work as always by the way.

mike4
01-07-2014, 03:21 AM
Two containers of Lubricant , possibly from a grateful customer.
Thats how I keep my OP Rum supply topped up.

Nice work even if it pi$$ed you off while completing the task.
Michael

John Stevenson
01-07-2014, 04:24 AM
My Dear Friend John,

In your second picture I can't help but see a bottle of some sort of "solvent" just in front of the blue handled hex wrenches.

What is it? Does it help? Or is it indeed a lubricant instead?

Just curious,

Your Friend John

That's the central heating. :o

jmarkwolf
01-07-2014, 08:03 AM
That little cock up by whoever ? cost me about two hours extra, 3 triangular boring tips, 4 solid carbide end mills

Clumsy bastard.

:)

John Stevenson
01-07-2014, 09:27 AM
Lol :D

loose nut
01-07-2014, 11:39 AM
Maybe you should have given this job to Mohamed.:D

ahidley
01-07-2014, 06:25 PM
I dont mean to hijack the thread. But it appears as you guys are talking about a steel that "work hardens"? That is a PH steel (Stainless Steel Round 17-4 (type 630)) is one like that here in the USA. Anyway, my question is, assuming that is what you are using, how do you get the chip breaker to work? I always end up with razor wire from hell. If the carbide bit gets dull then its as hard as the clumsy bastard says "witches tit". I since have changed to using a ceramic bit and that works wonderfully and lasts at least 10x longer than carbide. Thus its many times cheaper than carbide in the end. But it still wont make chips, only razor wire from hell. It does not seem to matter what speed and feed I use. The bits have a built in chip braker. Its a little groove around the top of the triangle bit. You see this on 90% of bits. It seems to work on everything EXCEPT this PH steel. (PH = precipitation-hardening)

John Stevenson
01-07-2014, 06:55 PM
Hijack all you want, Doesn't upset me but you mentioned stainless steel and this is medium carbon steel.
Took it to the hardening shop and expected to get it back later today but they were busy so it won't be ready until the morning.
It's having 15 thou of case hardening glued on.

Reason these wear is use or rather misuse. This one is an old design of fork truck where the drive is via a torque converter and forward and reverse is electrical.

Now if they drive steady, stop, reverse etc they last ages but get some hot shot who goes from flat out forward and straight into reverse without braking and these splines are under tremendous pressure and soon develop play. From then on it's a downward spiral.

95% of my machining is done with TPUN style triangular tips for three reasons, one is you get 3 edges compared to 2 on other type of tips

I can use the same tip on external and internal boring tools but the main reason is I bought about 150 boxes of 10 about ten years ago for absolutely peanuts. :)

Back to the central heating :D

Many, many years ago just after I came out of my apprenticeship, I started work at a truck garage as a lowly fitter, this would be 1968 and as most of us have endured things were a lot different then.
H&S for one was unheard of.

The truck garage was big, cold, draughty and most of the time because of what was in the garage and what was hanging out, the doors were never shut. result was in winter it was bloody freezing.

Add to this because of a lack of planned maintenance the reliability of trucks wasn't that good meaning we spent a lot of time out on breakdowns which was also bloody freezing !!

Start of the cold weather the boss would walk across the road to the off licence and buy two bottles, a bottle of whisky and a bottle of brandy [ he didn't drink whisky ] and put these on top of the radio.

When you were cold or just come in from a breakdown you made a coffee and tipped a small slug of whiskey or brandy in, whatever you fancied. Just enough to warm you up, probably 1/2 a cap full.
No one was ever rolling drunk or pissed in any way but H&S would have a baby nowadays.

I must admit I have kept that acquired taste and at the end of a day I have a drop in my coffee, don't bother during the day, it's not that cold in my shop now but last thing and when I get in the house knowing I don't have to go out again it nice to put the central heating on. :)

Arthur.Marks
01-07-2014, 08:25 PM
No, ahidley. Same acronym, different meaning when coupled with medium carbon steels. "PH" is commonly used for "Pre-Hard" for the latter. It may not be technically correct but is extremely common. In my previous reply, all I meant is material supplied with a hardness about ~30HRC.

ahidley
01-07-2014, 09:05 PM
Ok point taken. But never the less does anyone know how to make "chips" vs my razor wire from hell when turning the stainless 17-4.PH?

lakeside53
01-07-2014, 09:50 PM
Assuming your lathe has the grunt and rigidly, deeper doc, more feed. And.. real chip breakers. But.. sometimes.... it just won't break easily and little short blue springs are the best you can do.

.RC.
01-08-2014, 06:37 AM
Can gearotic cut those splines?

Alistair Hosie
01-08-2014, 03:05 PM
Take it easy John especially on those pub pies with last years date on them LOL seriously have a great year and enjoy retirement as far as you can buddy regards to you and Gert from Alistair and Bronwen. Alistair

John Stevenson
01-08-2014, 05:06 PM
Can gearotic cut those splines?

Yes, no problem but because of the way it works, small cuts and lots of them it's not a quick process, guessing about 45 minutes to an hour.

http://www.stevenson-engineers.co.uk/files/gearotic%20motion%2010_20%20spline.jpg

Basically fill the boxes in and it spits out the shape and from there you can get the code of a 4 axis CNC.

In the example above you put in the DP, 10 in this case, alter the stub from 1 to 0.5 to give the 10/20 form and change the angle to 30 degrees which is the default for involute splines.

From the info given on screen, to cut this requires an end mill 0.0923" maximum. Doesn't mean to say you need this size, just that it can't be any bigger but the program will correct to code to suit the cutter.

Upside of Gearotic is that you can do many non standard things with it and it's well worth the price. It's a brilliant get John out the $hit program

.RC.
01-09-2014, 01:26 AM
Thanks, truly is an amazing bit of software for the price...

One day I will get my CNC mill.... One day...