Making a new drive block for the Scotch Yoke

[Shawn]

I recently bought a Douglas 10.5 shaper that was in pretty decent shape. The only real issue with the machine is the drive block in the Yoke seems to have either worn down or was never the correct size to begin with. When the shaper is working the drive block makes a clunk at the beginning and end of each stroke due to the gap between the block and the yoke. I would have probably just ended up living with this issue as with the amount of use any of my tools get it would probably never get worse.

A fellow member here on the forum asked me what the size of the block was and then offered up a chunk of NiBrAl, I had to do some research to even know this was an aluminum bronze alloy and pretty tough stuff. Thanks Dallen, the block arrived in the mail today. It's bigger than what I need so I will have to sort out a way to hold it in my bandsaw and see how much I can save for other projects. The generosity of professional and hobby machinists is something I have not seen anywhere else, online or in life in general.

If someone has a shaper that is in good working order and doesn't have the clunk at each end of the stroke I was hoping you could measure the gap between the block and the yoke for me. I haven't measured the gap in mine but I'll bet it's close to 1/16th of an inch.

Thanks again Dallen, the block is sitting on my desk just begin me to get into the shop.

[dallen]

glad to see it arrived safely. it should last you a life time once you get it machine out and in the shaper.

DA

[Arbalest]

I bought a small piece of Aluminium bronze some years back, it turned very nicely.

[Sunset Machine]

 The gap in my 1910 shaper is pretty small, maybe a thou or two. I don't recall seeing any slop. There's a pivot at the top of the yoke where it connects to the ram, might be a place for a knock too. Oil ports on both of them here. Cold and dark out there right now, but I'll try to remember to take a closer look this evening. In the meantime here's an old picture when I found the thing:

[Shawn]

Thanks guys, I can tell from the picture there is a definate difference in the gap between your shaper and mine. I get the feeling that the drive block was never a tight fit on my shaper, the rest of the machine is in great shape and doesn't show any significant signs of wear. Even the drive block doesn't have the appearnce you would expect from a part that was worn down. I will hopefully get the new block cut out this weekend and will aim for a thou under to start with.

Cheers
Shawn

[Sunset Machine]

I was able to slip a .010 feeler between the yoke and block. The upper pin though, that one is pretty hard to get any tools on but loosening the ram clamp and wiggling the stud might get it to tell a story.

[big job]

Shawn although I do not own a douglas but I have no block movement there (with my fingers) and have no knocks.  I have been
(right or wrong) squirting #90 gear oil in there and on bull gears and we use it a lot.
sam 

[Shawn]

Thanks for the information guys. I got the new block built and installed. There is now 0.005 gap, I also installed a spacer made from HDPE between the forward pivot arm and the casting to keep that arm from shifting left and right. There is no more loud knocking sound and the tell tale marks I was getting on the work on the return stroke are gone. She is cutting nice and smooth now. The audio in the video seems much louder than in person, the clicking sound is the auto feed for the table. I also built a spacer block so I can get rid of the Armstrong tool holder and hold the bits directly in the clapper.

Shawn

[dallen]

(10-04-2014, 04:45 AM)big job Wrote: Shawn although I do not own a douglas but I have no block movement there (with my fingers) and have no knocks.  I have been
(right or wrong) squirting #90 gear oil in there and on bull gears and we use it a lot.
sam 

May be the wrong stuff but I use chainsaw bar oil, if it will stay on saw chain running it will stick to the gears in my shaper.

(10-09-2014, 01:06 PM)Shawn Wrote: Thanks for the information guys. I got the new block built and installed. There is now 0.005 gap, I also installed a spacer made from HDPE between the forward pivot arm and the casting to keep that arm from shifting left and right. There is no more loud knocking sound and the tell tale marks I was getting on the work on the return stroke are gone. She is cutting nice and smooth now. The audio in the video seems much louder than in person, the clicking sound is the auto feed for the table. I also built a spacer block so I can get rid of the Armstrong tool holder and hold the bits directly in the clapper.

Shawn

Shawn it looks to be running nice and smooth, how did the material machine, no problems I assume since you have the Douglas up and running.

DA

[Micktoon]

Nice video Shawn , shapers seem so graceful for a machine tool, a bit like a real fire .....you can just sit and watch quite content, very relaxing

  Cheers Mick.