Bobtach repair/modification - dimensions of parts required.

[Luthor]

I am in the process of modifying my old style bobtach to accept the new style locking lever and wedge components and was wondering if anyone has a Bobtach in pieces that they could get some sizes for me. The part I will be making next is called a Pivot Assy. in the parts catalogue (P/No: 6704240). This item is approximately $90.00 Australian each and would be quite easy to make if I had a dimensioned sketch to work to. I will also be making the pivot (P/No: 6704248) but that I can work out myself.
I have already made the levers after being shocked at the price of these from Bobcat Aus. at $154.00 each. So if anyone can help with a fairly accurrately dimensioned sketch of the parts listed above it would be greatly appreciated. By the way, a complete new Bobtach is over $3000.00 in Australia.

 

[coreya3212]

http://www.preseeder.com/service/tachallmanuals.cfm

Good Question Luthor. The plate plans are everywhere is seems, but this is all I could find. I didnt go through them all to see if there are dimensions or not, but you may get lucky.
This link below is the same question I think from another forum. The other links seems to be broken. Good Luck.
http://www.tractorbynet.com/forums/build-yourself/56969-bob-tach-quick-tach-dimensions.html

 

[Tazza]

http://www.preseeder.com/service/tachallmanuals.cfm

Good Question Luthor. The plate plans are everywhere is seems, but this is all I could find. I didnt go through them all to see if there are dimensions or not, but you may get lucky.
This link below is the same question I think from another forum. The other links seems to be broken. Good Luck.
http://www.tractorbynet.com/forums/build-yourself/56969-bob-tach-quick-tach-dimensions.html

Luthor - give me more details if you can.
I currently have a 763 bobtach that i have removed the lower pivot points. The part where the pins run at the bottom.
Even e-mail me taz38sup at yahoo.com.au i can give you a phone number and i can try and give you any details you need.

 

[Tazza]

Luthor - give me more details if you can.
I currently have a 763 bobtach that i have removed the lower pivot points. The part where the pins run at the bottom.
Even e-mail me taz38sup at yahoo.com.au i can give you a phone number and i can try and give you any details you need.

Yeah i got that price too! it was crazy, i need a set of levers and springs. The wedges are still there. Any sizes you need, just yell as its all in bits, as much as it can be at least.

 

[Luthor]

Yeah i got that price too! it was crazy, i need a set of levers and springs. The wedges are still there. Any sizes you need, just yell as its all in bits, as much as it can be at least.

Thanks Tazza, this is a picture, from one of Trihonu's posts, of the item that I want to reproduce. Do you have one that you can measure up? Is it made in one piece? The part numbers listed are from the 763 manual.
I will be making the standard version not the extended one.
Any help will be appreciated.

 

[Tazza]

Thanks Tazza, this is a picture, from one of Trihonu's posts, of the item that I want to reproduce. Do you have one that you can measure up? Is it made in one piece? The part numbers listed are from the 763 manual.
I will be making the standard version not the extended one.
Any help will be appreciated.

I believe i have that part still, i'll try and measure it tonight. If you haven't heard from me send me an e-mail to remind me

 

[Tazza]

I believe i have that part still, i'll try and measure it tonight. If you haven't heard from me send me an e-mail to remind me

http://users.tpg.com.au/tazza_/6_PivotDetail.jpg
You will have to zoom in to read the sizes.... sorry.
Its made out of 1" stock. I'm not sure how the round puck is attached though, i can't see welding marks but it has to be secured pretty tight as there can be a lot of load on here if the wedges get stuck. There is a hole through the recess of .660" for the bolt to pass through.
I hope thats of some use, if you need more detail i can sand blast them and take pictures with the vernier on it.

 

[Luthor]

http://users.tpg.com.au/tazza_/6_PivotDetail.jpg
You will have to zoom in to read the sizes.... sorry.
Its made out of 1" stock. I'm not sure how the round puck is attached though, i can't see welding marks but it has to be secured pretty tight as there can be a lot of load on here if the wedges get stuck. There is a hole through the recess of .660" for the bolt to pass through.
I hope thats of some use, if you need more detail i can sand blast them and take pictures with the vernier on it.

Thanks Tazza, that was fast service. I think you have given me enough information to start making them although I am confused as to the 1" stock you mentioned, is that the round section, because the other sizes are bigger than an inch.
Do you have the other end pivot, the one that attaches to the wegde, as I will be making them as well?
Thanks Again.

 

[TriHonu]

Thanks Tazza, that was fast service. I think you have given me enough information to start making them although I am confused as to the 1" stock you mentioned, is that the round section, because the other sizes are bigger than an inch.
Do you have the other end pivot, the one that attaches to the wegde, as I will be making them as well?
Thanks Again.

I measured one of mine. This is what I found.

 

[TriHonu]

I measured one of mine. This is what I found.

The piece is machined from one block of steel. The round pin is not welded on, it was turned from part of the original blank.

 

[Luthor]

The piece is machined from one block of steel. The round pin is not welded on, it was turned from part of the original blank.

Thanks Trihonu, I think I will keep a copy of your drawings for future reference. What software did you use?

 

[TriHonu]

Thanks Trihonu, I think I will keep a copy of your drawings for future reference. What software did you use?

It is a free CAD program from eMachineShop.com.
You design parts in 3D and specify the machining operations, tolerances and material. You can then specify how many pieces you want and the program will quote you price. If you want the parts, the order is placed via the web and the CAD drawing is sent to them to produce the parts.
The program is easy to use and will render in 3D shaded or wire-frame.

 

[Luthor]

It is a free CAD program from eMachineShop.com.
You design parts in 3D and specify the machining operations, tolerances and material. You can then specify how many pieces you want and the program will quote you price. If you want the parts, the order is placed via the web and the CAD drawing is sent to them to produce the parts.
The program is easy to use and will render in 3D shaded or wire-frame.

Tazza or Trihonu, do you have access to the lower pivot that you could measure up for me?This is the hexagonal piece that attatches to the wedge and the spring sits over it. I also need to know the diameter and length of the wedges which I thought were made from 1.25" stock but they actually are a little smaller I believe.
I so far have made the pivots mentioned above and the bobtach levers and will post pictures soon.

 

[Tazza]

Tazza or Trihonu, do you have access to the lower pivot that you could measure up for me?This is the hexagonal piece that attatches to the wedge and the spring sits over it. I also need to know the diameter and length of the wedges which I thought were made from 1.25" stock but they actually are a little smaller I believe.
I so far have made the pivots mentioned above and the bobtach levers and will post pictures soon.

I have them, i'll need to beasure them up for you. I'll try my best to get them for you tomorrow. If not, e-mail me so i remember to do it!

 

[Tazza]

I have them, i'll need to beasure them up for you. I'll try my best to get them for you tomorrow. If not, e-mail me so i remember to do it!

Sorry, i don't have any piccies but see if you can work it out from these:
1.125" hex, thats measures from flat to flat the slot cut in it is .58" wide and .373" deep. The hole for the pin is .9" up from the bottom of the cut and is 1/2" diameter. The whole "pin" is 3.89" long. One end is the hex, the other is machined down to .8" and is 2.175" long to the shoulder of the hex.
I hope that makes a bit of sense.... You have an idea in your head of how it looks, if i missed anything just tell me and i can try and work it out for you.
Wedge pin diameter is 1.21, 230mm long. The square plate on the end is 1" wide, 1/2" thick 1.5" long, 1/2" down from the top is a .53" hole in the middle. Hopefully thats enough to get you out of trouble.

 

[Luthor]

Sorry, i don't have any piccies but see if you can work it out from these:
1.125" hex, thats measures from flat to flat the slot cut in it is .58" wide and .373" deep. The hole for the pin is .9" up from the bottom of the cut and is 1/2" diameter. The whole "pin" is 3.89" long. One end is the hex, the other is machined down to .8" and is 2.175" long to the shoulder of the hex.
I hope that makes a bit of sense.... You have an idea in your head of how it looks, if i missed anything just tell me and i can try and work it out for you.
Wedge pin diameter is 1.21, 230mm long. The square plate on the end is 1" wide, 1/2" thick 1.5" long, 1/2" down from the top is a .53" hole in the middle. Hopefully thats enough to get you out of trouble.

Thanks Tazza, that's exactly what I was after. Would you mind re-checking the .373" dimension as I can't visualise that size working and also the 230mm length of wedge, is that the total length including the tab on the end or just the round body length?

 

[Tazza]

Thanks Tazza, that's exactly what I was after. Would you mind re-checking the .373" dimension as I can't visualise that size working and also the 230mm length of wedge, is that the total length including the tab on the end or just the round body length?

The wedge length is the entire length including the tab.
Yeah, .373 can't be rite, add 1 to that. 1.373"

 

[Luthor]

The wedge length is the entire length including the tab.
Yeah, .373 can't be rite, add 1 to that. 1.373"

Thanks again Tazza, the lower pivots are done so now it's on to the wedge pins and bushes.

 

[Luthor]

Thanks again Tazza, the lower pivots are done so now it's on to the wedge pins and bushes.

Here is the progress so far, all that I have to do now is make the long bushes that the wedge pins fit in and the weld on pivot that the handle swings on and start welding it all together.
It will look something like this when finished.
Tazza, would you mind measuring the pivot hole in the handle, this is the only thing I am not sure of and I want to keep everthing standard for interchangeability.