Choosing The Right Flex-hone®

Flex-Hones® are a great addition to every machinist’s bag of tricks. They’re essential for getting the best finish on cylinders, guides, etc. When we say best finish, we don’t mean smoothest. Flex-Hones® are intended to create a consistent cross hatch on the bore surface so that oil has something to cling to. Without this cross hatch, the oil will simply flow away without doing its job.

Let’s talk a little bit about Flex-Hones®. You may know them as ball hones or dingleberry hones, grape hones … gotta love creative machinists!

By definition, the flex-hone® is a resilient, flexible, honing tool with a soft cutting action. So what does that mean? It means that flex-hones® adjust to the cylinder surface. That’s why they’re used after the cylinder has been sized with rigid honing stones.

There are 3 factors in choosing a flex-hone – Abrasive, Grit and Size.

Abrasive

Flex-Hones® are available in several abrasives – silicon-carbide, aluminum oxide, alumina zirconia and diamond are most common in engine building/machining. Each of these abrasives has a purpose.

Silicon-Carbide is generally used on aluminum and cast iron but can also be used on brass and non-metallic materials. Silicon-Carbide is the most common abrasive in automotive work.

Aluminum-Oxide is used on hard materials such as hardened steel, hardened aluminum and other hardened metals. One of the most common applications for aluminum-oxide flex-hones® in engine building is Nicasil (nikasil) cylinders.

Aluminum-Zirconia is used on brake rotor flex-hones® among other things. This abrasive incorporates man-made zirconia with aluminum to create a rugged abrasive that is ideal for ferrous and non-ferrous metals.

Last, but not least, is Diamond. This abrasive is great for heat treated steel, high nickel stainless steel, chromed or plated material, MMX aluminum alloys and more.

Grit

You already know about grit. The higher the number, the finer the grit, the less material is actually removed. Flex-Hones® are available in the typical range of grits, from 20 to 800. The most commonly used grits for engine building work run from 120 to 400.

Choosing The Right Flex-honeEvery Flex-Hone® is color coded for fast identification of the hone’s grit. You’ll find this color-coding on the tip.  Refer to the list below to determine what grit you have.

Grit        Color
20           Brown
40           Purple
60           Gray
80           Orange
120         Silver (no color)
180         Red
240         Navy Blue
320         White
400         Yellow
600         Pink
800         Light Blue

Size

Whatever size cylinder you’re working on, odds are there’s a Flex-Hone® that will fit the bill. They start at 4mm (5/32”) and run all the way up to 24-1/2”. (NOTE: Goodson doesn’t carry every single size, but if you need a size other than what is stocked, let us know and we’ll order it in for you).

Flex-Hones are made oversize so you need to choose the size based on the size of your cylinder. If your cylinder is a non-standard size select the next largest size. For example, for a cylinder that has been machined to 3-3/8”, choose a 3-1/2” hone. The “flex” that’s build into the Flex-Hone® will adjust to the size difference.

As always, if you have any questions about Flex-Hones®, feel free to contact the Goodson Techxperts™ at 1-800-533-8010 or check out these related articles:

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Comments

  • Goodson Tools & Supplies - January 09, 2020

    if this is going to be a re-ring, then we recommend the 120 grit silicon carbide flex hone (#BG-350) for cast rings in high nickel blocks and the 320 grit (#BG-350320) silicon carbide for moly rings. Also lots of honing oil and 8 to 12 strokes per cylinder and a good cleaning afterwards, then you are good to go. Please let us know if you have any other questions.

  • Kerry Dancy - January 09, 2020

    I am working on a 51 Hudson with a 232 6cylinder high nickel block, 3.5" bore. Would the Flex Hone in 3.5" work, using the 240 or 320 grit?

  • Ron Smith - December 25, 2019

    I have a Briggs lawn mover engine with a 3 inch bore. What size brush hone should I use? What grit do you recommend?

  • Goodson Tools & Supplies - May 14, 2019

    As long as you are just re-ringing you will need to remove the scale and re-establish the cross hatch pattern using a flex hone with 320 grit and clean honing oil. I recommend about 10 to 12 strokes per cylinder and then do a super cleaning job and you will be good to go.

    Bore size = 3.4440-3.4450" (87.500-87.530 MM) so you will need to order BG-350320 $74.99

  • William Bell - May 14, 2019

    I am changing rings on my 2011 Ford Focus 2.0L Duratec engine which ball flex hone do i need to get the cross hash in the cylinders Thanks

  • Goodson Tools & Supplies - February 18, 2019

    Hi Leonard,

    How deep is the ”small scratch”?

    Generally we would use the following:
    For that 4.030” diameter use the 4-1/8” ball hone with 320 grit # BG-418320. This is a 4-1/8” ball hone with 320 grit. Run this tool at around 350-400 RPMs. Use lots of honing oil and hone for 10 to 45 seconds per cylinder. If you have any other questions, feel free to call our Tech Services Department at 800-533-8010.

  • Leonard Belvin - February 18, 2019

    Ls 6.0 punched to 4.030 have a small scratch from oil ring not going in right putting it together what size hone should I use 4” or 4 1/8 and what grit ?

  • Benny knotts - February 06, 2019

    I have a 1998 Johnson outboard.I want to hown the cylinders that are 3.1880 And wanted to know which one would work best for that type of material and size?

  • Goodson Tools & Supplies - January 08, 2019

    Hi Nick, With an 81mm bore, we suggest you use a 3-1/4" (82.6mm) flex-hone. Goodson has that size available in 4 different types – 320 Grit Standard Duty Silicon-Carbide (Order No. BG-325320), 120 Grit Standard Duty Silicon-Carbide (Order No. BG-325), 120 Grit Heavy Duty Silicon-Carbide (Order No. BGD-325) and 240 Grit Aluminum-Oxide (Order No. BA-325240).

  • Nick - January 08, 2019

    What size ball hone would I use for a 81mm bore?

  • Steve Scheide - November 27, 2018

    high I have two outbiard motors Onehas a bore size that is approx 1/4" larger than the other Could I order the tool for the larger size and use it on the smaller as well or maybe even in between both size cylinders?

  • Tanner Gibson - September 26, 2018

    I have a 0.5026" bore in cast iron and I need to get a surface roughness of 120 Ra. What grit should I use to achieve this? Thank you.

  • Triston - May 16, 2018

    I have a 5.3 v8 l33. It has a bore of 3.78 . Would a 41/2 ball Flexhone work to make a good crosshatch or will I have to get a smaller size?

  • Janet Tapp - October 06, 2017

    Hi Christopher,
    Thanks for the great question! These Ultra-Finish Plateau Hones are very fine grit; in the range you are looking at. We recommend you go up a size when selecting a Ultra-Finish Hone. The bristles will give slightly to accommodate the size difference.

  • Christopher - September 30, 2017

    Janet,

    Two questions… I need between 400-600 grit plateau hone, but the soft hones only list diameter, not grit. Second, if my bore us 76mm, do i go up a brush size or down? It’s right on the break between two sizes. Thanks!

  • Janet Tapp - September 29, 2017

    Christopher, Janet Tapp (advertising manager) here. We recommend you use our soft plateau hones to accomplish plateau honing. Check out this article from the blog: Flex-Hones 101 (https://goodson.com/blogs/goodson-gazette/flex-hones-101) for more details.

  • christopher - September 29, 2017

    Can a flex hone be used for a plateau finish? My understanding is you knock the peaks off but keep the valleys. Seems flat stones would do that, but I’ve heard that flex hones or brushes can…?

  • dave - July 20, 2017

    Ernie,

    We just to match the bore size and we recommend a 320 grit Silicon-Carbide Flex hone. Example: 4" bore – Part # BGD-400320 $122.99 also use lots of fresh clean honing oil and maybe 12 to 18 strokes per cylinder and you should be just fine. Call with any other questions or write if you wish.
    thank you,

    dave

    dave

  • Ernie Brezniak - July 20, 2017

    Hello I’m looking to put new piston rings in my 6.0 ls based Chevy.I would like to know what ball hone should I use to get a nice cross hatch for my new piston rings it’s a stock 4in bore.I would greatly appreciate if you could leave me a part # so I can order the product.

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