OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Victa pole pruner attachment - home built extensio

I have just picked up a Victa Tornado trimmer with a pole pruner attachment but the two together are still a bit short for the job. I am about to make an extension piece to go between the trimmer and pruner using a straight shaft from a dead Pope 33cc trimmer.
I have already stipped the shaft and it is splined both ends.
Next up was breaking down the clutch and the trimmer head for the two female splined pieces. After a bit of work on the bench grinder I have them nearly ready for attaching the connectors to match the Victa system.
The clutch piece is the bigger of the two and I will drill and tap it to accept the Victa male connector. The one from the trimmer head will need to have a new piece made to replicate the Victa female connector.
The final items to join the sections together will be some 32x3.0 aluminium tube for joiner sleeves.
The pics also show the bearings that supported the parts in the Pope

I'm a little concerned that the thinwall aluminium tube might not be strong enough for the job once it is extended like that. It might be a good idea to reinforce the tube section that is close to the powerhead - that is the one that will experience the greater bending moment.

My old (1980s) Echo has a steel tube outer, rather than aluminium tube. If you could replace the first aluminium tube (the one at the powerhead end) with a steel one of the same dimensions, it would be twice as strong.

When the pole saw is running it is a dangerous object, and to me the idea of risking its support breaking under load, is quite unattractive.

Always a good idea to play it safe. Thanks for the suggestion grumpy

Well it is done. A quick test run proved it would do the job but as grumpy expected it was a bit flexy but more so in the middle. The tube needs strengthening for long term durability.


I believed it was strong enough to cut the 5 or 6 branches I needed to cut and it has proved so.
Having finished this now I reckon the best long term option would be to use tbe powerhead and chainsaw attachment separated from their respective tubes and connect a single piece larger diameter tube between them with a straight single piece driveshaft running in the tube.

That sounds good, Diablo. I'm not clear on how you would make a single piece long shaft though, unless you have access to a milling machine with a dividing head to cut the splines. If you are going to make a shaft, I suggest you make it from steel, just so it will have assured long-term durability.

I'm not sure where I would source the shaft just yet. Obviously the outer tube will be a bit easier. Here is the 'after' shot of the tree. Once the canopy was cleared with the pole saw I used the stihl to shorten the trunk sections. I could have just cut the trunk and let the whole thing fall but there was too much height to be sure I could miss the fencing and/or the power lines. Better safe than sorry especially when power lines are involved.

I'm no arborist Diablo (in fact my tree-felling methods have disgusted members here in the past) but I don't think it will be easy to produce a design for a shaft that long, that runs stably. The shaft will be subject to a phenomenon called "whirling": the middle of the span inevitably runs just slightly out of true and centrifugal force causes it to run further out of true, which in turn increases the centrifugal force, and it breaks catastrophically. The only solution is to have intermediate bearings along the shaft, inside the outer tube, to support it. You could use a substantial steel outer tube, and locate nylon bearings along it every 3 feet, and the problem would hopefully be overcome, but to be safe it would need to be bench-tested before running it under load and standing near it.

You were probably saved from "whirling failure" of the shaft up to now, by the joiner you had in the middle of the shaft. Chances are the joiner was not all that loose in the outer tube. If you could inspect the interior of the tube you'd probably find signs of contact by the joiner.

Sorry grumpy I was not too clear about my design suggestion. The intent behind use of donor parts from another trimmer is that I would also use the inner bearing supports. The extension I built maintained the existing bearings from the pope sbaft and provided adequate support for the shaft to prevent whirling issues.