Technical A bit of machining. Re-drilling a flywheel.

This will be part of a separate series just showing machining. In this video I show how I redrilled a total of three flywheels. I redrilled one 9" and two 11" clutch flywheels to take a 10" clutch. I used my rotary table for the first time and found that an improvised counter really paid dividends. By the end of the third one I felt I had a good process going. In a separate video I will go into more detail about the bolt pattern relationships for the Early Ford clutches. Follow along as I virtually teach myself to use the milling machine and rotary table. If you enjoy it please check my other videos and SUBSCRIBE. Mart.

 

Nice, the rotary table comes in handy. Or you can lay it out in CAD and get the X & Y numbers. This is where a good DRO is as good as gold.

 

CAD? This is a traditional web site, how about a little geometry and trigonometry?

 

I was told there would be no math on Mondays!

 

Jig boring coordinate calculator is on this website as well as in machinery's handbook where you just need to know the number of holes and PCD. https://littlemachineshop.com/mobile/bolt_circle.php
I do usually use a rotary table, like in the is photo of an 8BA flywheel, but you need to bear in mind that as you're likely to be be working off the radius to arrive at a PCD, any layout error will be doubled.
I also re-drilled this flywheel to accept a modern clutch pressure plate, although I'm just securing a slack ring gear here.

 

Thanks for the responses fellas. I don't do too good on winding the handles, I tend to miscount and get things out by one turn. I don't have a DRO and don't think my machine work is serious enough to warrant one. I was particularly pleased with the little click counter. Good point on the radius, made above. Like I say I'm learning all this stuff so any helpful comments are welcome.

Oh yeah, I did use a free cad drawing programme to draw it up and work out the angles.

Thanks again for the interest.

Mart.

 

You really need to put a digital readout on the machine. You can get them reasonably priced and they save you much more time and money in the long run. They make it easier to make long moves accurately. The cost of scrapping one part makes a digital readout worthwile. Once you use one, you'll never be happy without one.

Drilling flywheels can get an amatuer machinist into a world of hurt . I would not attempt to learn how to do machine work on a flywheel.

 

Digital read-outs are nice, but a travel indicator will work in a pinch.

 

My dad was a toolmaker for 39 years. When I decided to use a T5 (!) behind my flatty I took the flywheel to a machine shop to get drilled. A month later I went to get it back not done. Asked the Ole Man if he could do it. 'I can do that blindfolded.'-his exact words. Went to his basement where he had his drill press (it's still there). Slapped it on the table, drew a few lines, drilled it. Then...this was nuts to a 20-sumthin' kid...he tapped the holes WITH HIS DRILL PRESS! I sure miss him. Thanks for making me think of him this morning.

 

QUOTE="57 HEAP, post: 13498277, member: 18344"]CAD? This is a traditional web site, how about a little geometry and trigonometry?[/QUOTE]
I have taught trig to a lot of people. I worked with a real U-boat commander from Germany, he was a great tin knocker. I offered to teach him, he showed me what he did, trial and errors on small pieces of scrap until he got it right.

I have laminated charts that make bolt circles very simple and I have used that quite a bit. My DRO has since crapped out, not worth fixing and 30 years of use on a 25 year old mill have rendered it as beat up. I'll be looing for a better used one or may go new once I retire. I have been dialing things off for the past 5 or so years. Still pretty accurate.

When I got to one shop at work, great model shop and busy. They gave me a tough milling job and the only open machine was a Van Normal universal mill... no DRO and the dials were .250 instead of the .200 on most... gulp... Well, I cranked the part out and it passed inspection.

 

In machining, accuracy is everything.

Digital readouts are to machining what the rubber tire was to the wheel. Its a really big improvement .
I learned how to machine using a dial indicator on a milling machine, so I know how much time and effort it takes to machine parts that way. Buy an inexpensive digital readout and the resale price of your milling machine goes up at least the cost of the DRO, and you have the use of it for years to come. With a DRO you can accurately make a 10"
move in about 10 seconds with no tolerance stackup. They are exceptional at quickly locating holes. How long and how many moves would it take you to drill the flywheel above. Whether using a DRO or conventional milling without a rotary table, calculating the locations would take the same amount of time.
The actual machining using a DRO would take maybe 30 minutes. Using a dial indicator for your moves would probably take half a day. Like you say, it can be done.........but you have to look at how many jobs you will do in a lifetime and the amount of time expended for even the simplest of jobs. An equally important downside to making multiple moves/measurements to define multiple hole locations is the increased possibility of making a mistake. Just using the handles on the machine may work, but then you have to deal with the slop in the machine itself and hope you didn't get any play in your moves.

 

Oh yeah, the DRO makes setups fast, I can crank out tooling fast too. I had one job in the shop years ago, a series of flat plates with many holes in them, one had over 130, all different sizes and a lot of tapped holes. I really had to keep my wits about me not to mix them up. Everything from the same X, Y datum made it a cinch.

 

I was a machinist for thirty years (same shop), when Trav-a-dials first came out we put them on our (wore out) lathes and it really improved productivity.
When I bought a new 18x80 lathe for my home shop I put one on it, love them.

 

This is a very interesting thread. I’m just an ol’ diesel mechanic, can someone please explain what trigonometry is (I know it’s math, but I never went passed algebra 2). How is it used here? Is the post about drilling new holes in a flywheel to mount a different clutch? Thanks so much for teaching me!


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Doc, the original post was my link to my video showing how I redrilled a flywheel to take a different size of clutch. the discussion then touched on other ways of doing it. trigonometry was mentioned in passing and not really anything to do with this job, though in some circumstances it might be relevant.

in the video I establish the correct relationship to generate holes on a specific bolt circle and then use the rotary table to generate the correct angular relationship between the holes.

It's all early Ford orientated.

Mart.

 

Add one more DRO worshipper to the list. Have one on my Index 745.

 

There are many different ways to machine a part depending on what kind of machinery and what types of tooling you have available. In Marts set up he has a "rotary table" he can set on the milling machine. As it's name implies, it rotates when you crank it by hand. The top surface of the rotary table is round with a flat top surface. To use it, you align the center of the table with the spindle of the milling machine. This is the basic starting point for almost anything that is round. You find the center of something and then you make all your moves in relation to that center location.
If you have a rotary table and you want to drill a hole pattern like a circular pattern for a clutch, all you need to know is the radius of your bolt circle and how many holes the pattern has. With that information in hand, you simply crank the machine either left/right/in/out. It's your choice, you just simply need to move the center of the part (which is centered on the rotary table and clamped down tightly) a distance equal to the radius of the hole pattern. THEN you drill your first hole. The side of the rotary table has 1 degree graduations marked on it. 360 of them. If your bolt circle has 6 holes,you divide 360 ÷6=60 degrees. So you need to drill another hole every 60 degrees. So you simply crank the handle from 0 to 60 and the rotating table will now be lined up for the second hole. Crank it again and now you are at 120 degrees.....60 more=180 and you continue untill you reach 300 degrees and all the holes should be in the correct location.

But what if you don't have a rotary table? Then you must locate each hole by moving the work table (Not rotary table) of the machine a specific distance in both the "x" and the "y" axis. You still have to find the center of the part before you start, but now instead of rotating the part around in a circle and drilling holes based on 60 degrees of rotation, the part is going to stay in the same place on the work table (clamped in place). The whole table will now need to be moved left/right (X axis) AND in/out (Y axis) specific distances to locate each hole location.

Now, to answer your question! What is trigonometry.
A RIGHT triangle has three sides and two of them are at a 90 degree angle to each other.
As you make either of those two legs longer or shorter the third side of the triangle will change BOTH it's length AND the ANGLE .

The MOST IMPORTANT thing to realize is that there is a relationship between all 3 sides of a RIGHT triangle. Basically if you know what two of the "factors" or "dimensions" of the RIGHT triangle are, you can calculate the other dimension or angles of the Right triangle.
Why is that important?
Going back to the 6 hole pattern we previously discussed. Every hole was 60 degrees. We also knew the radius of pattern. If we consider the radius of the pattern to be one leg of a RIGHT triangle and we know we will be at a 60 degrees angle, we can use that information to calculate the other sides of the triangle.........which will be the correct location for one of the holes in your pattern.

Basically if you know the length of one side of a RIGHT triangle and one of the angles besides the 90° RIGHT angle, TRI-gonometry will let you calculate the other dimensions contained in the triangle by using a table of ratios. It's really pretty simple, much easier than algebra. The basic thing is that there is a small reference book (or on your computer) that gives you the correct ratio to apply to get the correct answer for the angle and length you are working with.

Hope this wasn't long and boring, but I wanted to explain that there are multiple ways to accomplish machining the same type of part depending on what someone has to work with.

 

Thank you so much! Not long or boring at all, more like fascinating. I never knew or even thought of stuff like that. I have had the opportunity to play with a lathe to turn something down, but never anything like the flywheel drilling. Very cool! I wish I could pass on some of my wisdom to you guys, but unless you need to know anything about electronically controlled Diesel engines, that’s about all I have. Thanks again for the explanation.


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Pick up a basic math book at a bookstore and get one with a trig section. Machinery Handbooks have a trig section in them, I have some small books with all the trig function tables in them... before calculators came along. Look up SOHCAHTOA, which explains the main 3 functions. Sine = opposite/hypotenuse (longest side of a 90 degree triangle), Cosine = adjacent/hypotenuse, Tangent = opposite/adjacent.

 

Hey Mart, Look at what i just found in the back corner of the garage.

 

Mart, Thanks so much for sharing your knowledge and making a great video
to explain it.

 

"When I bought a new 18x80 lathe for my home shop I put one on it, love them."

Wow! 18 x 80. Wish I lived near you.

 

Henry, I'm guessing 11", 9" plus marine or industrial. I think it has the finer gear teeth too, so British (compatible with Lucas starter.)

Mart.

 

Thanks fordy, I enjoy busying myself by making them.

 

There are some excellent tutorials on any given math subject on youtube. You can just do a search on G--gle, using a string like:
youtube trigonometry tutorial

You will get a list of results, and by looking your way through the list, you will find the style of teaching that appeals to you. Here is an example:

Bob

 

I have a lathe, mill, and have a rotary table that I have used many times to drill flywheels and other rotary parts where it was critical to place the holes correctly. Unfortunately, other than a digital caliper. I only have the original rotary dials on my machines, so when doing procedures than are not done regularly, it can take a lot of re-calculating and re-checking to make certain everything is accurate.
The old adage, measure twice, cut once applies to any job in metal or wood working.
I would love some of the digital devices to make these jobs easier, but I am not doing enough of those kinds of jobs any more, to make it worth the cost of doing the digital upgrade.
Bob

 

In the interest of full disclosure, I did get one hole out of position on the first one I did. I went past the first point, wound back and came to it again. I must have not fully taken out the free play though. Luckily I offered up the clutch cover after I did the second hole. I had to make the second hole the first and do a new second hole further round. So the first flywheel I did has one hole extra. I was thinking I can fill the hole with a sawn off bolt to compensate for the lost weight. The third one I did had all six holes spotted first so a pressure plate can be offered up to check all is well.
The more you do the better chance of getting it right. I've only done three and the second and third came out good and the first will be usable with a little rework.

Thanks for the interest.

Mart.

 

Nice video, my only suggestion would be to use a center drill first, followed by the tap drill. Center drills are short/rigid (improved location accuracy) so, they do not wander like a longer drill bit might.
Cheers


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Started in a machine shop in the early 70's. Boss was smart enough to gradually fit the Bridgeports with DROs. These were Bausch + Lomb Accurite brand and were excellent for saving time and had .0005 accuracy.
Before all of them were installed, a few times I did operations using the .200 dial on the X & Y....what a PITA. Of course one of the old retired guys that was hired to clean the shop would laugh at me for "having to use digitals"
On very rare occasions, a glass scale might malfunction because oil somehow worked its way into the reader head. Got to be a specialist at cleaning those.

Later on when I retired and got a BP clone for home use, I spent the money and got a SONY 2-axis Magnascale for it. Sure is nice not to worry about glass scales.
A Magnascale would be a bit much for the home user.

If you look on Amazon or eBay, there's all kinds of DROs for not too much money; they are definitely worth it ! Make sure you understand what is being sold. Some ads show pictures of complete outfits, but the fine print says e.g "3 Axis DRO Display only" The scales are separate.
Majority that I looked at were all glass scales.

Some of the displays have Hole Circle calculations, and some have Trig functions too. Real time savers.

There was a Newell closed scale that came on our Nardini lathe. They aren't that cheap, but work well, and there's no problem with swarf or oil getting into the system.
Not pushing that brand, but if you're interested;

http://www.newall.com/
then look under Technology

Re using a rotary table, always turn one way with a bit of tension on the lock(s). If you overshoot, back up and take the backlash out before going for the setting. This also applies to using the handwheel dials on a mill (or lathe for that matter) There's always going to be backlash on leadscrews, and needs to be considered when machining.
Rare would be the machine that would be equipped with ballscrews to eliminate backlash, but I've seen them.

 

Mart, I did a lot of threading on the lathe, and you learn very quickly that you have to keep the backlash out, or one pass without eliminating the backlash, and you have wrecked the whole job. Same with the rotary table.
Bob