Finding the center of these hubs

[junkyardjeff]

Usually the wheels I bought had holes for the axle but these wheels are not drilled,what would be the best way to find the center.

[Ace-Garageguy]

A lathe.

OR...use a compass to draw a circle the diameter of the wheel.

Use the procedure below to find the center of the circle.

Cut the circle out carefully and hold it against the wheel, and poke through the center with something sharp...unless you're like me and can eyeball it within a few thou....plenty close enough.  

Easy, no measuring, no math, and this guy actually uses unnecessary steps (but I'm not going to watch a bunch of YT videos to find someone who doesn't).

 

Edited November 30, 2023 by Ace-Garageguy

[Ace-Garageguy]

3 more easy ways...but they all require a circle the diameter of your wheel.

 

[Bugatti Fan]

Have a look on the Micro Mark tool site and see if you can buy a miniature centre square. It is a tool specifically designed for marking across the centre of circular pieces. Drawing lines taken from two positions on the circumference the lines will intersect at the centre of the circular piece. Micro Mark has a 2.5 inch one for about 15 dollars. Look in the measuring equipment part of their website. The photo will be self explanatory as to how it is used. A good long term small investment for the tool box.

Scratch builders and converters will find one of these tools invaluable. The other tool I use constantly is a miniature engineers 90 degree set square. Also a good investment.

In the UK, Squires, Shesto or Proops might be the best places to source one.

Bill suggested a lathe as a bit of tongue in cheek humour, and yes it is dead easy to do on my little Unimat. But not all of us have access to one so the centre square is the best alternative without having to resort to using geometry on plastic card or whatever.

Edited December 11, 2023 by Bugatti Fan

[stitchdup]

Draw an equilateral triangle on the circle with each point touching the circle. now measure half one side, and mark on all 3 sides. draw a line at 90 degrees to the triangle wall from this point on all 3 sides, towards the centre on each line and the point the lines meet will be the centre

Edited November 30, 2023 by stitchdup

[NOBLNG]

This method will work for your wheels also. No math required...and doesn’t cost a nickel! 🙂

 

Edited December 1, 2023 by NOBLNG

[ColonelKrypton]

This is the tool you need - a machinists center finder square

https://www.amazon.ca/Grizzly-H5604-Center-Square-2-Inch/dp/B00012YCU6/

It should be a simple matter to make your own from some bits of polystyrene sheet.  Ideally you would make your corner 90 degrees but anything would work. The hard part is gluing in place the long straight strip that bisects that angle and you can make it as big or as small as your need dictate.  I have made a couple over the years and they have served well.

cheers, Graham

 

[bobss396]

I save old wheel backs that go unused on some builds for a guide. Most of the time I can find one that fits. Metal washers as well. When I had lathe access, that was a breeze. I like the Micromark centering gauge. I will have to get one.

[Mike 1017]

1 hour ago, bobss396 said:

I save old wheel backs that go unused on some builds for a guide. Most of the time I can find one that fits. Metal washers as well. When I had lathe access, that was a breeze. I like the Micromark centering gauge. I will have to get one.

 I agree the wheel backs are the way to go.

[R. Thorne]

If the center hub is not bigger than .350”, this works good in conjunction with a pin or other device or tiny drill for the centering hole.

[junkyardjeff]

Looked at the Micro Mark website and found plenty of tools to buy.

[Skip]

Looks like everybody and their brother recommended the right tool for the job, the Center Finder Square, back when I worked in the machine shop as an Inspector for Boeing, I used one all the time. The Center Finder takes all the mathematical steps out of figuring out the actual center in two steps check at 0 Deg. (North) rotate a quarter turn 90 Deg. (East) marking both measurement as you make them and end up with a crosspoint in the center of the circle. - Easiest Method

Better Cheaper Method - The other quick and dirty (easy) cheap method is using a set of dial or digital calipers or micrometer to measure the O.D. of the rod/circle then divide that by 2 giving you both the Radius and the Center of the Circle. R = D/ 2 = (Center or Radius) then set your calipers to that number and measure at 0 deg and 90 deg and there's your center just like the center finder. This would probably be my preferred method as a modeler as many of us already have a set of calipers, vernier, dial, digital and a calculator or pencil and paper.

Personally, I would probably never chord or arc a circle to find its center, there are so many other quick, simple ways to accurately measure the exact center point. That is unless you just have to impress someone with your vast knowledge, then by all means go for it! Even as an Engineer (now Retired), I would never Arc or Chord a circle, that's for math, geometry or trig classes, (ancient history for most of us).  I'm all for the easy way that a non-technical person will understand and pick up quickly, remembering how to solve the problem again and again.

You can also find Center Finder Squares on eVilbay new or used for cheaper than Micromark or other precision tool sellers, quality is going to be the same of the Chinese made stuff and Micromark's (Chinese Stuff). On eBay under used Machinist's Tools search, you might come up with a Starrett, Lufkin, Brown & Sharpe, Mitutoyo or other reputable American Made tooling sometimes cheaper than the new Chinese made tool. For what we do as modelers a cheap Chinese made center finder will work just as well as anything.  Even then, unless you are finding a whole lot of centers for rods, wheels... it might be overkill, I'd rather have a decent set of 6' dial or digital calipers with multiple uses than a center finder square with a specific usage. If you own and use a lathe, then a center finder square would pay off in time saved, otherwise it's a neat widget that won't get used as often as you imagine it will

[Bugatti Fan]

At 15 bucks the Micro Mark (probably Chinese) centre square will be plenty good enough and inexpensive enough for the needs of the vast majority of modellers out there.  Accurate enough for most of our needs I would say.

Agreed that as an engineer myself that Brown and Sharp, Starrett and Mitsutoyo are much better quality tools like the Rabone Chesterman and  Moore & Wright brands in the UK. If any of these quality tool brands can be sourced second hand, great! But how often do they come up on evil bay at the right price?

 

Edited December 1, 2023 by Bugatti Fan

[Skip]

OK, finally had the time to peruse eBay for the Center Finder Squares and a couple alternatives all of which are less than Micromark and new items. I looked under both preowned and used machinist tools with zero hits, which is no surprise because the items change all the time. I have seen them there before though, so if one is patient and doesn't need it right now, keep looking until one shows up.  So, if you just can't wait or need it now here are three listings for new center finders which will give you an accurate way to find center in round stock.

WoodRiver Key Chain Center Finder - WoodRiver Pen Blank Key Chain Center Finder | eBay @ $6.99 + Shipping (U.S. Seller)

Small Plastic Center Finder - Plastic Center Finder For Round And Sexangle Woodwork Tool | eBay  @ $7.69 Free Shipping (Seller is in China)

Taylor Tools Center Finder Square - Taytools 1-1/2" Machinist Center Finder Square 150720 469508 | eBay  @ $12.99 Free Shipping (U.S. Seller)

The only issue I have with Micromark and others who sell inexpensive Chinese made tooling is the fit and finish. I have had several tools that I've had to deburr or break an edge which could cut the user under normal intended use. If the seller is calling the tool "Tool Maker or Tool & Die Maker Grade" then it should be ready to use right out of the packaging (no corrections needed to use safely). I've also had a few that surprised me with superior fit and finish, superior grade tooling right out of the package. 

There you go...

 

[Straightliner59]

On 11/30/2023 at 6:38 PM, junkyardjeff said:

Looked at the Micro Mark website and found plenty of tools to buy.

The Micro Mark catalog is the current equivalent of the Sears Wish Book, when I was a kid.

[Straightliner59]

On 11/30/2023 at 9:16 PM, Skip said:

Looks like everybody and their brother recommended the right tool for the job, the Center Finder Square, back when I worked in the machine shop as an Inspector for Boeing, I used one all the time. The Center Finder takes all the mathematical steps out of figuring out the actual center in two steps check at 0 Deg. (North) rotate a quarter turn 90 Deg. (East) marking both measurement as you make them and end up with a crosspoint in the center of the circle. - Easiest Method

Better Cheaper Method - The other quick and dirty (easy) cheap method is using a set of dial or digital calipers or micrometer to measure the O.D. of the rod/circle then divide that by 2 giving you both the Radius and the Center of the Circle. R = D/ 2 = (Center or Radius) then set your calipers to that number and measure at 0 deg and 90 deg and there's your center just like the center finder. This would probably be my preferred method as a modeler as many of us already have a set of calipers, vernier, dial, digital and a calculator or pencil and paper.

Personally, I would probably never chord or arc a circle to find its center, there are so many other quick, simple ways to accurately measure the exact center point. That is unless you just have to impress someone with your vast knowledge, then by all means go for it! Even as an Engineer (now Retired), I would never Arc or Chord a circle, that's for math, geometry or trig classes, (ancient history for most of us).  I'm all for the easy way that a non-technical person will understand and pick up quickly, remembering how to solve the problem again and again.

You can also find Center Finder Squares on eVilbay new or used for cheaper than Micromark or other precision tool sellers, quality is going to be the same of the Chinese made stuff and Micromark's (Chinese Stuff). On eBay under used Machinist's Tools search, you might come up with a Starrett, Lufkin, Brown & Sharpe, Mitutoyo or other reputable American Made tooling sometimes cheaper than the new Chinese made tool. For what we do as modelers a cheap Chinese made center finder will work just as well as anything.  Even then, unless you are finding a whole lot of centers for rods, wheels... it might be overkill, I'd rather have a decent set of 6' dial or digital calipers with multiple uses than a center finder square with a specific usage. If you own and use a lathe, then a center finder square would pay off in time saved, otherwise it's a neat widget that won't get used as often as you imagine it will

This is excellent information, imparted very well. It embodies the text I highlighted, above. Something that directly relates to that, is that writers often  omit the simplest aspects of accomplishing something, because it's such a fundamental part of the task, that they simply forget just how important it is. 

[Bugatti Fan]

The Micro Mark and Taytools centre squares appear to be better than the plastic ones and the keyring versions as they have positive locating edges to place against the circumference of the circular piece like you would also find on a premium expensive branded product.

At between 12 and 15 bucks each, less than one would pay for a fret of PE parts!

Like all small tools it's a case of horses for courses!   Plenty good enough for most of us modellers.

Skip has pretty much summed up the differences between premium make tools and  the inexpensive tools that most hobby tool suppliers carry. I still have and use all the quality tools that I bought way back when I was an engineering apprentice. But, in most cases in reality modellers would use those sort of tools infrequently unless into true model engineering, so the inexpensive tools would serve quite well for most.

Edited December 5, 2023 by Bugatti Fan

[NOBLNG]

I’ll admit I am a bit of a tool junkie myself and have a combination square set with the protractor and center finder heads that I use quite often. I also have quite a few tools that I bought and only used once, or not at all.🥴 For a one time or occasional need, the method I showed in my link would certainly be accurate enough. JMO.😎

[Skip]

After looking at the WoodRiver Center Finder, I went ahead and bought one. I just checked it against my Center Finder Square using 1/2", 1/4" and 1/8" bar stock, it is dead accurate.  So, anyone looking for an accurate budget friendly tool to find the center of round stock, this one fits the bill. I'll be pulling it out before pulling my Center Finder Square to use on the workbench, it is accurate and robust enough for any of the duties a modeler will ask it to do and then some! Looks exactly like the one attached below.

WoodRiver Key Chain Center Finder - WoodRiver Pen Blank Key Chain Center Finder | eBay @ $6.99 + Shipping (U.S. Seller)

 

Edited December 11, 2023 by Skip
Fixing Autocorrected Stuff