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Author Topic: Inline-four crankshaft  (Read 214186 times)

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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #195 on: March 18, 2015, 01:39:50 AM »
Irony: I've got an old Elox EDM (vacuum tube) sitting here, that I haven't found time to get working yet!! :roll:
And to add to the irony- I've got the rotary drive for the EDM which would allow EDM'ing the needed threads in the crank, rather than having to tap them!
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Offline Peter Jack

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Re: Inline-four crankshaft
« Reply #196 on: March 18, 2015, 05:49:00 AM »
Jack, if you haven't tried them look up Power Twist Plus vee belts. They're a really neat linked belt that you buy in bulk and put together at any length you require. They virtually don't stretch, last about forever and run much smoother than a conventional vee belt. I've taken the vibration out of a couple of my drill presses just by switching to them. Oh yes, the other advantage is they don't slip. Any belt drive machines in my shop that are more than a couple of years old are converted because it's a far superior system to the conventional vee belt.

After a ringing endorsement like that I wish I was profiting from the advice. I just really like the product. It does what it says and more.  :-D :-D :-D

Pete

Offline Koncretekid

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Re: Inline-four crankshaft
« Reply #197 on: March 18, 2015, 06:12:16 AM »
Jack,
My RF-30 mill looks like a dead ringer for the Harbor Freight 590.  How do you raise the spindle drive to accomodate longer tool bits without loosing alignment?

Also, how's your weather?  My wife and I were planning to make the drive to Colorado starting tomorrow, but woke up to this!

Tom
« Last Edit: March 18, 2015, 06:17:14 AM by Koncretekid »
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Offline wobblywalrus

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Re: Inline-four crankshaft
« Reply #198 on: March 18, 2015, 11:44:18 PM »
Jack, the modern carbide insert tooling might work best.  The little bits have materials, coatings, and edge profiles we cannot duplicate on our old skool stuff.  There are specialized inserts for hard materials.  www.doriantool.com or www.meshertool.com


Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #199 on: March 18, 2015, 11:47:58 PM »
... How do you raise the spindle drive to accomodate longer tool bits without loosing alignment?...
The spacer blocks are parallel-ground on two faces.
Yes, your mill looks pretty much like mine. Does yours have 7 3/8" travel in the Y direction?
I believe winter is on its way out here. A lot of snow melted the last 10 days. Had about 2-3" today, but no more in the near forecast.
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Offline Koncretekid

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Re: Inline-four crankshaft
« Reply #200 on: March 19, 2015, 05:24:39 AM »
Yes, 7-3/8" in the Y direction.  By the way, I was reading some info about the Rong Fu mill drill (also sold under Enco, Harbor Freight, and many other names) and learned how to tighten the gibs and the bed nuts.  Got my lash down to .25 mm (mine's metric) and movement in the table down to about .002".  Then I read an interesting conversion to full CNC using ball screws, stepper motors, and an available computer program.  Fascinating stuff for an old mill drill.

The alignment issue in the Z direction I was referring to was when you run out of travel and need to install a longer drill, for example.  Only way to move the spindle up on the round column messes up alignment.  Only way I know is to leave in the smaller drill inserted into the previously drilled hole, raise the spindle and lock it with the drill in the hole.  Then raise the quill which allows you to put in a longer drill or whatever.  Just a pain.

You mentioned you put a stepper motor on the Z axis.  Did you convert to ball screw?  How does the stepper motor prevent the quill from pushing up while milling or do you depend on the quill lock?

Good to hear you're not expecting any more snow. I may be passing your exit Saturday afternoon.

Tom
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #201 on: March 20, 2015, 12:22:23 AM »
Your're right, that having to re-orient the spindle after raising/lowering the head is a pain; haven't figured a way around it.
No modern stuff like stepper motors here; my downfeed motor is from an old barbecue grill! Replaced the flashlight batteries with a 6VDC supply and potentiometer, V-belt drive to a pulley in place of the original crank handle. I call it an "electric" feed, vs. "power" feed. However, I haven't come to any boring/drilling/turning situation that it wouldn't handle okay. I just remove the belt to use the mill normally.
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #202 on: April 01, 2015, 01:20:42 AM »
Finished the milling on the crank today. A word to the wise: if you plan to modify a billet crank, have the maker send it to you prior to any hardening and/or Nitriding! It took me a long time to realize that carbide cuts 42-hardness 4340 alloy just fine- IF you can avoid the tool touching any of the Nitride- which is a problem, as the Nitride depth is quite varied and located unpredictably. In general the Nitride is .003"-.004" deep and can be ground off the surface. But many places it was up to .040" deep, which ruled out grinding it all away.

Now I get to find out how "tappable" the heat-treated 4340 is... :roll:
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #203 on: April 01, 2015, 11:47:26 PM »
Hopeful news: Spot-faced, drilled, and tapped the first couple of holes okay. :-)
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Offline tauruck

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Re: Inline-four crankshaft
« Reply #204 on: April 02, 2015, 12:10:52 AM »
We once sent in a Crower crank for balancing and the machinist couldn't even drill a hole. :-D

Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #205 on: April 05, 2015, 12:13:07 AM »
... a Crower crank... machinist couldn't even drill a hole...
He should have hand-ground through the surface hardening (Nitride, induction hardened, whatever), then it would have drilled okay.

24 holes spot-faced, 22 drilled, 9 tapped; only 18 more to drill, and 31 more to tap... 8-)
Broke just one tap so far- operator error. Got lucky and worked the broken piece out.
« Last Edit: April 05, 2015, 12:15:15 AM by Jack Gifford »
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Offline fordboy628

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Re: Inline-four crankshaft
« Reply #206 on: April 05, 2015, 06:40:45 AM »
... a Crower crank... machinist couldn't even drill a hole...
He should have hand-ground through the surface hardening (Nitride, induction hardened, whatever), then it would have drilled okay.

24 holes spot-faced, 22 drilled, 9 tapped; only 18 more to drill, and 31 more to tap... 8-)
Broke just one tap so far- operator error. Got lucky and worked the broken piece out.

Jack,

I'm keeping my fingers crossed for you on the tapping.    When, or if, a tap starts to "drag" while cutting the threads, change to a new tap.   Although I'd bet real money, (or beer), that a guy with your machine tool experience already knows that.
 :cheers:
Fordboy

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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #207 on: April 09, 2015, 11:32:09 PM »
A milestone: crank machining done... gee, only 27 days... :-o Sort of glad I didn't keep track of how many hours...
Just a little more work with a Dremel and sand-roll to knock off a few remaining sharply-square corners. Then, after double/triple checking my blueprint of the magnesium segments, I'll see when (?) that job would fit into the local CNC shop's schedule.
« Last Edit: April 09, 2015, 11:36:13 PM by Jack Gifford »
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Offline Milwaukee Midget

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Re: Inline-four crankshaft
« Reply #208 on: April 09, 2015, 11:52:37 PM »
Nice bit of skill, patience and care with that, Jack. 

A race car is never done, but there's a huge sense of relief and satisfaction when a project get's to the point that you can put a line through it.

And THIS was a project.   :cheers:
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #209 on: May 16, 2015, 11:57:25 PM »
The shop finally scheduled the CNC shaping of the magnesium alloy filler segments- they expect to start on them about four weeks from now.

I think I've already "set a record" with this car; most money ever thrown at an engine project! Crane Cams has finally started building the unique pair of camshafts needed for my DOHC design- for a mere $1,600 each... :-o
« Last Edit: May 16, 2015, 11:58:57 PM by Jack Gifford »
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