New guy from Norway, planning a Bonelle grinder

[BizibilderParticipant @bizibilder]

I found that I had to redrill the threaded holes in the wheelhead arms in order to attach the guide block when building my Bonelle – It seems that there are various cumulative errors that eventually don't quite add up! I had real trouble trying to find out why the thing didn't fit!! Additionally I had the problem that my 2" square iron bar for the wheelhead block (C4) was metric i.e. 50 mm square (rather than 2" or 50.8mm) and had also been cleaned up on all four sides making the actual dimensions even less by a few thou all round. Not really surprising that it did not fit off the drawings.

So far this is the only part that has not fitted after being machined straight from the drawings. I am currently building the toolholder and have worked through the drawing in more or less the order that they are set-out.

The only modification I have done is with the bellows and their attachments. I will be using commercial rubber bellows and have designed and machined a set of attachments to allow the bellows to rotate as the front bar is rotated – otherwise the bellows would twist and prevent free movement of the bar.

Just to add – Don't alter the guide block.  Just reposition the threaded holes used to secure it.  You will have problems if you alter the block.  There are two positions for the leadscrew in the wheelhead guide (C8) that can be used and both will fit if you simply reposition the holes for the block.

Edited By Bizibilder on 03/04/2023 15:35:17

[BazParticipant @baz89810]

Welcome to the world of Model Engineering! You will find things don’t line up, bits are drawn wrong, 26 tpi threads are supposed to fit in 40 tpi holes, the list goes on. Although all these drawings, steam loco, traction engine and workshop tooling have been around for years the drawings are never updated, the pathetic excuse from all the sellers of castings and drawings is copyright issues, this is just a lame excuse, all that is needed is a sheet of corrections sent out with each set of drawings, please watch out for missing holes here, wrong size hole there etc. Rant over, I wish you luck with the Bonelle, not many finished ones exhibited unfortunately. Please keep us all updated on your progress.

[FulmenParticipant @fulmen]

Ok, you've calmed me down a bit. I just figured all the bugs world be fixed after all these years. It's an easy fix, I just had to make sure it wasn't one of my stupid mistakes.

I'll reposition the holes and reduce the height of the guide so it doesn't interfere with the mounting bolts. This is why I model everything in 3D before building.

[FulmenParticipant @fulmen]

BTW, I came across this yesterday: hexagonal paper bellows

Plain office paper covered in packing tape works like a charm, I just printed the template and scored the paper with a ball point pen. The pattern is easy to make, the width of the vertical lines is 3.46 (2*tan(60)) times the height.

[FulmenParticipant @fulmen]

What, you thought you got rid of me? Fat chance, I just don’t do much machining during the summer.

Here’s the progress so far:

[martin haysomParticipant @martinhaysom48469]

i too am building a bonelle. i have used a quorn type column so missed that alignment error. only by luck as i made the change because i think it looks better. i am also planning to use a small er collet spindle and rubber bellows possible car steering rack gaiters

[FulmenParticipant @fulmen]

Haven’t given up yet:

If I find a suitable motor I can start testing it as a tool post grinder, so that will be my next focus. IIRC the design calls for a 100W / 1500RPM motor, but that would only give a speed of around 1000m/min. The old Norton manual I’m reading in seems to recommend 2-3 times that depending on the application. Am I missing something?

I also need some wheels, would this be a sensible place to start?

https://www.aliexpress.com/item/1005004633960267.html

[noel shelleyParticipant @noelshelley55608]

You do not say what size wheels but at a guess I would look at the spindle running at 3 – 4000 rpm. I would build in a way to be able to balance the wheels and buy wheels fron a reputable supplier. not the one you mention ! A simple wheel balancer will pay dividends as the slightest vibration will spoil your work. Your spindle looks very short ? Noel.

[FulmenParticipant @fulmen]

Sorry, forgot to give the details. It’s for 4″ wheels with a 1.75:1 gearing on the pulleys. So 2500RPM give or take for a 1500RPM motor. But that’s only 800m/min (less than 3000sfm). Norton seems to recommend 4-6000sfm for most applications. Fine, it’s not 2-3 times but still…

https://www.airgraver.com/shaper/Tool%20Room%20Grinding.pdf

A wheel balancer sounds like a good idea. The bonelle documentation doesn’t really cover this bit, and I started this project without really considering it’s use as a toolpost grinder. So I haven’t prioritized learning how to actually use this yet.

The problem with reputable dealers is that they come with reputable prices. None of my affordable dealers seem to carry anything useful (Chronos and Arc Auro have some resin bound stuff). Recommendations are welcome.

 

[Wade BeattyParticipant @wadebeatty78296]

Fullmen,

Welcome from another Norwegian member.

i dont know if you have seen this but he makes many of his tools from aluminum.

http://www.metallmodellbau.de/MINI_BONELLE_1.php

http://www.metallmodellbau.de/Eigenbau-Universalspindel.php

 

Wade

[FulmenParticipant @fulmen]

Thanks, that’s useful.

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