Digger/excavator post driver

[Malus]

Looking for some advice from anyone who's got or has used a post driver on a small digger. I've made up a post knocker but after initial testing I'm not sure about the headstock mounting position. I looked at as many knockers as I could find before starting but settled on a design that's much like the protect p18.

 

My question is, when you have the knocker mounted does the weight and post cap face the cab or away from the cab? To me it would make sense to have it face the cab for slightly better visibility but in this configuration I haven't got enough crowd to keep the mast vertical when lifting it high up to start driving a post. If I change the headstock angle by 45° or 90° it makes it a nightmare to pick up/drop off. 

 

Alternatively with the weight and post cap facing away from the cab, it's easy to pick up and put down. Has a good range of workability from a tall post right down to ground level. Slight compromise in visibility. Do I just need to get used to it like this? 

 

I've seen protech ones mounted in both directions. I'd like to get it sorted asap so I can get some paint on it and put it to work.

 

[gdh]

The protech ones come with bolts to go either way. I like ours facing out so when you're knocking stakes you can just push up to the netting instead of lifting over. Also if a stake ever snaps it's less likely to get you or anyone nearby.

 

Edited August 12, 2023 by gdh

[Malus]

Ok thanks, some good points. I noticed you've got a chain to lift the post cap up with the weight. Do you find you need two people on a fencing job or does one man hop in and out of the machine? I've not added a chain here but instead a chain from the post cap to the bottom of the mast, so the weight of the mast and the dipper rest on the post. I was hoping I would be able to spike in a few posts at a time and drive them in one after another without having to get out of the machine. Trouble is with this arrangement is you have to lift the bottom of the mast to the height of the top of the post. Although I can't imagine that would be a problem in an 8t machine it might be a stretch for a 3t.

[gdh]

Yes, we always use two people so it's a bit different for us. One in the machine and one eyeing in the stake, it's worth the extra person because we can hit 100 an hour on a good day. Although we do space the stakes out on the floor first.

 

I looked at chaining to the mast but we knock a lot of 8ft strainers and gate posts and it would make that awkward, especially doing big hits on soft ground.

[doobin]

God you’re keen. You could have bought a secondhand p180 for £1800!

 

best mounting for me I find is to have the mast straight in front of the dipper. 
 

Matt Storrs (is he still on here? Can’t find him to tag him) gave me that great tip years ago- chain the plate to the bottom of the mast so as you can put a bit of pressure on the post, so you’re totally on the right track here!!! Makes it much easier to do on your own and easier on the machine too as it doesn’t wobbly all over the place on the first few hits.  I wouldn’t have it any other way. Leg on the ground, sliding the cap up the mast etc is all very well on a big solid tractor, but a digger requires a different approach. Also means you always have the full length of the mast available from the first hit, which is a benefit with the smaller weights on diggers. 
 

I agree with the above- two people makes it super quick. You shouldn’t have a problem lifting the mast up to the post top- as soon as you rest the chained clamp on the top of theit becomes much more stable. As you are transferring some weight from the digger to the post you can get away with less weight on the knocker too. You will get the hang of adjusting the mast angle each knock to keep the mast vertical and the plate in a ‘neutral’ position as the arm lowers with each knock on the post. 
 

I’d build a hitch for the back of your mast like mine so you have options. Play around with it and get the pin angles so that the mast almost touches the digger dipper when fully crowded back but make sure the ram arm can’t hit either- that’s optimum positioning and will let you get closer to posts. 

 

 

Edited August 13, 2023 by doobin

[Malus]

Nice one, thanks @doobin Sounds daft but it hadn't crossed my mind to mount it inline with the dipper... I guess I got blinded by the fact all the commercial ones I've seen are off set. I'll make up a mount and give it a go. 

 

It's not so much that I can't lift it over a post, more that when it's set up as in the photo above with the weight facing the cab, the geometry means it's impossible to keep the mast vertical when you lift it high. I think I'll stick with it facing out since you both have made some good points.

 

Tell me about it. I had been looking for a used one for about three months but I didn't find anything within a reasonable distance from home until I found a second hand p18 at auction. Got outbid and I think it sold close to £2.5k so that tipped me over the edge to make one. Optimistically thought it would take a day or two to build but probably more like five after doing all the fiddly bits. Althought it was all done in the evenings after work etc. Total cost under 1k Inc vat so happy enough and certainly learnt a thing or two.

[doobin]

The fabrication work looks good 👍🏻Now that you’ve developed your skills, how about welding a pin grabber screw hitch to replace the half hitch under your powertilt?

 

BMC will do you a plate with their excellent screw hitch on, then you will always have tight buckets with no play. It’s excellent for things like the post knocker in particular. 
 

I will try to find a picture of my powertilt with the screw hitch added. The plate they supply as standard is pretty much the perfect size so it’s a half hour job to cut the old hitch off and weld the screw hitch on. 

[hedge mong]

Do these have enough weight in them or does the Wacker bounce the digger?

I've seen these around but not sure however look good for gardens and rubbish access.

Currently using a suma on a 7495 which is pretty big and cumbersome.

 

[gdh]

10 hours ago, Malus said:

Nice one, thanks @doobin Sounds daft but it hadn't crossed my mind to mount it inline with the dipper... I guess I got blinded by the fact all the commercial ones I've seen are off set. I'll make up a mount and give it a go. 

 

It's not so much that I can't lift it over a post, more that when it's set up as in the photo above with the weight facing the cab, the geometry means it's impossible to keep the mast vertical when you lift it high. I think I'll stick with it facing out since you both have made some good points.

 

Tell me about it. I had been looking for a used one for about three months but I didn't find anything within a reasonable distance from home until I found a second hand p18 at auction. Got outbid and I think it sold close to £2.5k so that tipped me over the edge to make one. Optimistically thought it would take a day or two to build but probably more like five after doing all the fiddly bits. Althought it was all done in the evenings after work etc. Total cost under 1k Inc vat so happy enough and certainly learnt a thing or two.

I think commercial ones are offset so you can use them at any angle without the lift ram hitting the boom (depending on design). 

 

I hadn't realised how expensive they were now, we only paid £2400 for protech 300 about 6 years ago and that was new.

[Malus]

10 hours ago, doobin said:

The fabrication work looks good 👍🏻Now that you’ve developed your skills, how about welding a pin grabber screw hitch to replace the half hitch under your powertilt?

 

BMC will do you a plate with their excellent screw hitch on, then you will always have tight buckets with no play. It’s excellent for things like the post knocker in particular. 
 

I will try to find a picture of my powertilt with the screw hitch added. The plate they supply as standard is pretty much the perfect size so it’s a half hour job to cut the old hitch off and weld the screw hitch on. 

Thanks for the idea but no need! It's a hydraulic hitch. Spent too many years using a powertilt with a semi hitch so I made sure to have a hydraulic one when I got my own machine. There must be a better system out there though to avoid such a bit build height.