Small distractions: making a rail bender for under $10

Things have been  a little slow on the blog front of late in part because my hobby time has been spent elsewhere and because I’ve been making tools to help my cause which naturally takes away from actual layout construction. One such gizmo is the rail bender. Essentially an item older than the hobby itself, I remember seeing one of these in my very first issue of Model Railroader magazine. In that article they used an Orr bender to produce very neatly radiused bends for a traction layout. The opportunity to poke at a Fasttracks bender got me out of the arm chair and pouring through boxes looking for appropriate bearings and hardware. While I wasn’t able to find the right bearings I found most of the materials  in my stack of off-cuts. A trip to Princess Auto gave me everything else and left me seven dollars lighter.

The design chosen closely follows the Fasttracks model with accommodations for manufacturing process and personal skill level. Three bearings are employed, two fixed with a third bearing race moving between the fixed pair. I used a piece of 1/2″ 6061 aluminium plate for the body with a 3/8″ X 3/8″ slot up the middle to take a movable steel die block and on it the third bearing. I kept the tool body square rather than spend time making it a more ergonomic shape. Doing so makes it easier to machine and makes it easy to hold in a bench vice. The die block is captured on the top by an 1/8″ piece of plate with a slot just wide enough for the bearing spigot and bolt to pass through.

Rather than employ a spring to hold the die block firm against the leadscrew,  I opted to make a T-slot in the die block that slides over a correspondingly T-shaped end to the leadscrew. I’ve been exploring this method for use on another type of miniature bender and figured it was worth it to try it out here as well. Here you can see the die block (Cold rolled, 1018)  and cutter( W-1 drill rod). Some other construction photos follow.

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hardened T-slot cutter and along with bottom face of the die block

Un-hardened cutter

Un-hardened cutter

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Boring out slot ends in the top plate to .440″. Slot will be completed with 3/8″ slot drill running first up the centre and then each side; necessary for the non standard slot width.

Assembly starts with screwing the leadscrew into the lower body piece , dropping the die block over top of the screw followed by the top plate, then ancillaries such as bearings, spacers and bolts.

Functional rail bender

Functional rail bender

The rail roller is functional but unfinished in the following picture. The 33″ radius curved rail having just been formed.   Items that need seeing to include shortening of the stationary bearing bolts , finding or making a die block bolt with appropriate shoulder, drilling and tapping for top plate fixing bolts. A leadscrew knob is also in the cards though it’s a bit up in the air whether I’ll knurl it or machine grooves. Some form of marking would also help quicken set up and aid repeatability.

AH

2 thoughts on “Small distractions: making a rail bender for under $10

  1. Hi, Can you please give the exact plan measures and parts for this fret-bender ? How can you adjust the tool for 7,5″ , 9,5″ , 12″ , 14″, 16″ ,etc ???
    Thanks in advance…
    Costas

    • Hi Costas,

      I don’t have the tool on me right now but will update with dimensions when I do. I think it is about 3″X3.5″. To turn a tighter radius you screw in the middle bearing using the the long screw that is double nutted. I don’t know what the minimum radius is but it will likely do 12″ and up and may even do the smaller sizes. The layout could certainly be altered to achieve smaller radii at the design stage. One thing to consider if this tool is to be used for instrument frets is that the bearings have a small chamfer (about .03125″ @45 degrees) that may cause trouble. Small rims could be pressed over the bearings to alleviate this problem.

      Cheers for now,

      AH

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