2025-12-26

Last modified: 2025-12-26 20:51:14

• Tractor
• Old Bear Biplane

Tractor

Sprocket carrier now welded to axle:

Not an amazing weld but seems OK so far.

And honker now on bonnet instead of steering wheel:

We went for a razz in the garden, the tractor is very slow uphill despite the new lower gearing. I wonder if the "throttle conditioner" is maxing out below 100% throttle?

Also it makes some unpleasant knocking and crunchy noises intermittently. I think the bolts holding the motor and lay shaft mounts are not sufficient to stop them slipping, so I think the knocking noises is when one component or the other slips. The crunchy noise could be that when one of them gets cocked sideways the chain scrapes against something? Or could be bearings getting damaged in either the lay shaft or the motor.

I know that the chain tension is getting lost, so I am pretty sure the bolts are slipping, I need to come up with some way to lock the adjustment once it is set. And then see if that also cures the crunchy noise or not.

Old Bear Biplane

I think I want this at 2/3 the scale I have modelled it. This is actually really annoying to do in FreeCAD. I almost want a Macro or something that can automatically scale everything.

I can easily fit 4 planes' worth of the 4mm plywood parts on the table:

I can start on the fuselages today. I have some 3x3 pressure-treated material, I will trim the edges on all 4 sides until it is 50x50, and hopefully the pressure-treating won't leave an ugly stain. And then needs cutting to 180mm lengths.

• trim all 4 sides until it is 50x50
• cut to 180mm lengths
• cut 4mm thick slot in tail for horizontal stabiliser
• make a jig for cutting the chamfers?

I've made a start:

Using the jig to chamfer the front of the nose worked really well.

I tried to use a similar jig to thin down the fuselage towards the tail but it doesn't work very well because once you've done the first 2 cuts the bottom surface is no longer flat and doesn't sit properly against the jig surface. So I need to make something that clamps it more solidly on the square section that doesn't get cut down.