[macrafic]

I have two binding issues regarding the electric flap installation.

When I put the delrin blocks on the ends of the flap weldment, they went on awfully tight. After installing the weldment into the aircraft, the flap handle took a lot of force to move the weldment in the blocks. After I installed and clamped down on the additional center delrin block, it became even more difficult. I certainly do not want to submit my flap motor to those kinds of forces. Is it common to have to take something like a Dremel drum sander and remove a mm or so from the inside surfaces of the delrin blocks, or is there another fix for this?

The 2nd binding issue is the motor itself. Per the instructions, I ran the motor to its extreme ends, in order to find the middle, prior to connecting it to the flap weldment. At both ends, when the leads were reversed to reverse the motor direction, the rod spun, but would not extend or retract further. In both cases, I had to give a manual assist with my hand to get the extension/retraction going. One thought I had was that this might be common at the extremes and, during useage, once connected, the motor would never see these extremes. However, at this point, that is nothing more than conjecture on my part. Is this common, or might I have a bad motor?

Anybody run into the same problems I have?

Thanks!

 

[Lionclaw]

Mine was a bit tight at first too. I found some rust on the unpainted parts of the weldment that might have been causing some problems. I scuffed the ends up with scotchbrite, deburred the ends of the pipe, and added a bit of grease. Problem solved. Did you put washers in the center block to act as a spacer for the material that was removed when you cut it in half? Is the weldment straight? Do you have to deflect the weldment to get it into the center block?

As for the motor, if I'm understanding you right it sounds like it's working like it's supposed to. Normally it will be captured by the flap weldment and will not spin. If you turn it on without it hooked up to anything it should just spin and not extend or retract.

 

[RKellogg]

tight flap bearing blocks

We solved the tight bearing block problem by making a low-budget reamer from a 8 inch length of same-diameter 4130 steel tube and gently shaving the ID of the bearings to the correct size. The bearing block material is difficult to abrade, (Dremel attempts did not yield satisfactory results) but cuts cleanly with a sharp edge. The homemade reamer peeled off two beautiful, thin shavings as it was turned, leaving a clean, smooth surface on a hole that was still round. Maybe not quite as nice as the original hole, but the correct size. To create the reamer, make two diametrically opposed axial sawcuts about an inch long in the end of the 4130 tube, sharpen the clockwise edges with a jewelers file, and bend the edges to adjust the diameter. Taper (by gentle bending) the leading end of the reamer to create a pilot that keeps the tool centered in the existing hole. Gradually remove this taper to cut the lower part of the blind hole. I clamped two Visegrip(tm) pliers to the other end of the tube to make handles, but one could weld a tee handle on the other end of the tool.
Make small shaves, then increase the diameter by bending the cutting edges further. Clamp the split middle bearing block halves together in a vise before reaming to get a round bore of the correct diameter. Make shallow cuts, try to keep the reamer perpendicular to the block. A wee bit of friction is not a problem. Do the reaming at room temperature if possible, since the UHMWPH has a much larger thermal coefficient of expansion than the 4130 steel flap actuator torque tube. Initially our bearing blocks were so tight that assembly was difficult. And of course, making the sawcuts in the middle bearing destroys any semblance or roundness in that part. Putting washers in the sawgap did not sound like an 'aviation-quality' solution, maybe on a lawn mower... Perhaps Van's will eventually come up with a better solution on this part, having their machinist jobshop create two halves before boring the hole... And why aren't the bolt holes pre drilled?
Let me know how it goes... - Roger Kellogg

 

[macrafic]

Mine was a bit tight at first too. I found some rust on the unpainted parts of the weldment that might have been causing some problems. I scuffed the ends up with scotchbrite, deburred the ends of the pipe, and added a bit of grease. Problem solved. Did you put washers in the center block to act as a spacer for the material that was removed when you cut it in half? Is the weldment straight? Do you have to deflect the weldment to get it into the center block?

As for the motor, if I'm understanding you right it sounds like it's working like it's supposed to. Normally it will be captured by the flap weldment and will not spin. If you turn it on without it hooked up to anything it should just spin and not extend or retract.

I did forget about the washers in the center block, so thanks for the reminder. However, that only helped a bit. As I said, before I even installed the weldment, the blocks went on very tight. I had no rust on the weldment ends. When I installed the weldment, before installing the center block, it was very tight. So, I still am looking for suggestions. Thanks!

 

[macrafic]

We solved the tight bearing block problem by making a low-budget reamer from a 8 inch length of same-diameter 4130 steel tube and gently shaving the ID of the bearings to the correct size. The bearing block material is difficult to abrade, (Dremel attempts did not yield satisfactory results) but cuts cleanly with a sharp edge. The homemade reamer peeled off two beautiful, thin shavings as it was turned, leaving a clean, smooth surface on a hole that was still round. Maybe not quite as nice as the original hole, but the correct size. To create the reamer, make two diametrically opposed axial sawcuts about an inch long in the end of the 4130 tube, sharpen the clockwise edges with a jewelers file, and bend the edges to adjust the diameter. Taper (by gentle bending) the leading end of the reamer to create a pilot that keeps the tool centered in the existing hole. Gradually remove this taper to cut the lower part of the blind hole. I clamped two Visegrip(tm) pliers to the other end of the tube to make handles, but one could weld a tee handle on the other end of the tool.
Make small shaves, then increase the diameter by bending the cutting edges further. Clamp the split middle bearing block halves together in a vise before reaming to get a round bore of the correct diameter. Make shallow cuts, try to keep the reamer perpendicular to the block. A wee bit of friction is not a problem. Do the reaming at room temperature if possible, since the UHMWPH has a much larger thermal coefficient of expansion than the 4130 steel flap actuator torque tube. Initially our bearing blocks were so tight that assembly was difficult. And of course, making the sawcuts in the middle bearing destroys any semblance or roundness in that part. Putting washers in the sawgap did not sound like an 'aviation-quality' solution, maybe on a lawn mower... Perhaps Van's will eventually come up with a better solution on this part, having their machinist jobshop create two halves before boring the hole... And why aren't the bolt holes pre drilled?
Let me know how it goes... - Roger Kellogg

Roger, I'm a visual person. Do you have any pictures of this device you created?

 

[macrafic]

We solved the tight bearing block problem by making a low-budget reamer from a 8 inch length of same-diameter 4130 steel tube and gently shaving the ID of the bearings to the correct size. The bearing block material is difficult to abrade, (Dremel attempts did not yield satisfactory results) but cuts cleanly with a sharp edge. The homemade reamer peeled off two beautiful, thin shavings as it was turned, leaving a clean, smooth surface on a hole that was still round. Maybe not quite as nice as the original hole, but the correct size. To create the reamer, make two diametrically opposed axial sawcuts about an inch long in the end of the 4130 tube, sharpen the clockwise edges with a jewelers file, and bend the edges to adjust the diameter. Taper (by gentle bending) the leading end of the reamer to create a pilot that keeps the tool centered in the existing hole. Gradually remove this taper to cut the lower part of the blind hole. I clamped two Visegrip(tm) pliers to the other end of the tube to make handles, but one could weld a tee handle on the other end of the tool.
Make small shaves, then increase the diameter by bending the cutting edges further. Clamp the split middle bearing block halves together in a vise before reaming to get a round bore of the correct diameter. Make shallow cuts, try to keep the reamer perpendicular to the block. A wee bit of friction is not a problem. Do the reaming at room temperature if possible, since the UHMWPH has a much larger thermal coefficient of expansion than the 4130 steel flap actuator torque tube. Initially our bearing blocks were so tight that assembly was difficult. And of course, making the sawcuts in the middle bearing destroys any semblance or roundness in that part. Putting washers in the sawgap did not sound like an 'aviation-quality' solution, maybe on a lawn mower... Perhaps Van's will eventually come up with a better solution on this part, having their machinist jobshop create two halves before boring the hole... And why aren't the bolt holes pre drilled?
Let me know how it goes... - Roger Kellogg

PS. Regarding the "washers in the sawcut", I do remember at some point previously in the instructions for some other part (it has been a long time), that the Van's instructions suggested exactly this. So, while it may seem a bit "un-aviation", apparently, it is perfectly appropriate.

 

[RKellogg]

reamer pix...

Rich, I think the homemade reamer is still lurking under a worktable in the 'factory'. I will try to get a picture tonight. - Roger

 

[Bushcaddy]

adjustable reamer

Rich,

I didn't build an RV but did have several UHMW bearing blocks in my plane. I ran into the same issue with the holes being very tight. I got an adjustable reamer from grizzly, no reason it wouldn't work on Delrin. You can make fine adjustements and continue to spin the reamer in the holes until you get the desired resistance/friction: http://grizzly.amazonwebstore.com/G...src=froogle&utm_medium=CSE&utm_source=froogle

 

[RKellogg]

reamer in blind hole...

Two of the three bearing blocks are blind holes, they do not go all the way through the .75 inch thickness. It looks as if the adjustable reamers need about two inches of tail room.... ??

 

[swisseagle]

mesure first! Then shape tube.

Hello

It is the same like on the rudder pedals. The tubes are not exactly round after the cutting and welding.

1. Take a caliper and mesure the tube on about 4 to 6 stations.
2. Mesure the UHMW, it will be also not so round.
3. If it is only a small amount, then try to sand off the few tousends so that the tube gets more round or more equal to the nylon blocks. big differences can be squeezed in a vise, but be verry carefull, mesure often ans squeeze only a very small amount, the rotate tube by 30? and squeeze again. Then again sand them with emery cloth amd it will be smooth.

Takes about 1/4 to 1/2 hour per end.

Best regards,
Dominik

 

[gasman]

Use a spade bit the same size as the tube. Clamp the block down and use a drill press on the slowest speed.

The block that was cut in half, don't use washers just clamp it back together and re-drill it with the spade bit. It was amazing how well this works.

Be sure to check that the weldment is not warped. It might need some adjusting.