Camera Repaired -- Now Heavier, and Glidecam Problems!
 

Ok, so my internal speaker been fixed on my Canon XH-A1, it's been cleaned, and the firmware updated, so I brought it home, and strapped it onto my Glidecam 4000 Pro. I was expecting it to need minor rebalancing, but I wasn't expecting the camera to be heavier than it was before!

Prior to having the camera repaired, I used a total of 8 weights on the base plate (4 each on the front and back), and I had a drop-time of 3 seconds. The dynamic balance was pretty darned good too. Now, I have to have 10 weights on the base plate just to stop it turning upside down! With the Central Post almost all the way collapsed, my drop time is closer to 2 seconds. The dynamic balance is nowhere near what it was, and the camera wants to pan as I move.

I've spent nearly 4 hours trying to get it right... longer than I did when I first got the Glidecam.

Any suggestions? I was hoping to use my rig tonight at a charity event, but I may just go handheld instead!

Hi Julian..........
 

Bigger battery, perhaps?

Something mounted up top that wasn't there before?

Just shots in the dark.


CS

Chris,

I wish that were the case. I gave them the camera with nothing in it, nothing attached (not even a front element UV filter), and got it back the same way. I put the exact same accessories back on the camera (same battery, same filter, same SD card) and got the results I mentioned.

After writing the first message in this post, I decided to remove the extra weights (so I could regain some of my drop time), pull the central post out a bit further, and move the weights around a bit on the base plate. It's back in static balance again, but I'm flummoxed as to why the camera was *so* different. Nothing moved on the Glidecam during the day the camera was at the repair facility, and I've successfully removed and replaced the camera from the Glidecam in the past, without experiencing these balance problems.

I had my new setup balanced perfectly, then the following day my bogen 577 quick release adapter showed up. I marked the cameras location, added the adapter, and the added weight of the adapter, as well as raising the camera an inch threw everything off. I had to start all over with balancing. I figure its good practice....

I went through the same issue -- got a QR plate for the Glidecam so had to go through the entire process again. It was much quicker the 2nd time around. But this is baffling! It's the same camera with EXACTLY the same stuff attached to it or inserted inside it! Even down to the same tape! I've marked the position of the LCD screen as well, so that's not an issue. The camera is just heavier! Like I said earlier, I've got it static balanced again with the original weights after moving the weights on the base plate around, but it's not anywhere near as nicely dynamically balanced. After shooting this evening, I'll try some of Charles' suggestions to get the dynamic balance dialed in.

Here's the test I did earlier. It should be a bit better now.

http://vimeo.com/937588

Julian, you will find that after few months of rebalancing it many times (when you add WA, mic, then take it out and put it again) you will do it in no time.
I just had an emergency, where I couldn't use my A1 on GL and had to rebalance it for HV20. It took me 5 min at the most.
So keep practicing :)

I agree, practice makes perfect. But don't you think it strange that the camera would be completely top heavy... so much so, that it caused the Glidecam to flip over upside down?

I don't have a clue. It's strange.

I bet they left a hammer or something inside your camera by mistake...

Hahaha! Who do you think they are, King-Harbor Hospital? :-)

Out of curiosity, lol, did you check to see if the camera they gave you back had the same serial number? ;)

EDIT:

BTW, good to meet another Frost! Not a lot of us out there.

Hey brother! :-)

No, I didn't check the serial number... but I do recognize the dust! Ha! Yeah, it's my camera!

I used it this evening (eek, make that "last night") at the charity event and got some decent footage considering the run-and-gun nature of the shoot. Though the dynamic balance isn't perfect, the footage was way better than hand-held. Even the static stuff looked like it was on a tripod.

Pendulm-ing!
 

I bought a pair of small spirit levels, mounted them on the base plate of the Glidecam 4000 Pro, and rebalanced the rig while it was resting on its stand. I then picked it up, and watched as the rig moved off balance again and settled in a totally new attitude! Hmmm.

I made several small adjustments and got it so that it was balanced while holding it. I did the arc test, and measured the drop time at just under 3 seconds. I faced "north", and pointed the Glidecam "east" and walked forward, as if doing a tracking shot, and the Glidecam began to pendulum (the base plate stayed static as the camera moved with me).

In this case, my instinct tells me that there's too much weight on the base, hence it gets left behind when I move. But if I reduce the weight or shorten the center post, the camera will flip over!

Any suggestions?

what does it do when you spin it? does it spin flat?

I have a hard time spinning it without introducing wobble. That is, giving it a fair spin without user-induced unsteadiness. That said, if I spin it quickly, then use my free hand to control the center post so that I get it vertical again and at the same time slow it down a bit, it appears to spin flat -- even though I can feel through the handle that it's a bit lens-heavy. By holding the center post horizontal and allowing the rig to rotate in place I know that the camera is right-side heavy. I've been totally unable to correct that. When I do the arc drop test, the camera spins around "randomly", showing me it's not dynamically balanced.

I sent an email to Glidecam asking if I should give up on this 4000 Pro, or if anything can be done about it. When I hold my statically balanced rig in my hand, it'll slowly rotate to the right. If I rotate the handle by 180-degrees, it does not maintain its balance. To me this yells that the gimbal is not linear. There's also some play in the handle too. Add this to the fact that when I tighten the screws on the mid- and head plates, the COG changes (due to the plates distorting and/or moving under the different forces from each screw). This means I'm always chasing the balance. My rig may be front heavy in one test, then, when I move the head plate back and tighten the screws, it can be even more front heavy, or side heavy -- or who knows what -- because as the screws tightened, the plates moved slightly diagonally in relation to each other!

If the plates were secured in such a way that they could only move at exactly 90-degrees from each other, say, in a tongue and groove-type arrangement, that would surely help. But they're held aligned by screws which slide through a slot, and the slot simply allows too much play. I've seen the plates misaligned by 2-3mm during my adjustments. That may not sound like much, but it was enough to totally destroy the vertical *and* horizontal balance in a rig that was just a tiny bit out of horizontal balance!

My glidecam also would move when I turned the handle, I had definite gimbal alignment problems. I have worked as a machinist, so I was able to repair mine. it sounds like your is having similar problems

Julian,

Have you checked to see if the gimbal bearings need any oil. Because they are shielded and not sealed they might loose some of their smoothness and some oil could help. We had to add oil to the bearings on a rig we bought before we started making our own. We now suggest our customers check the gimbal every once in a while just to make sure everything is working correctly.

If you rig pendulums very much, it is bottom heavy. The strange thing is that you say your drop time is three seconds which should show very little pendulum effect. That is why I wonder about the bearings. If you tighten the handle bolt assembly too much, you can induce friction which would make a bottom heavy rig have a longer drop time.

Move the rig back and forth in front of you and see how much it pendulums.

If all else fails, take two aspirin and call me in the morning...

Tery
Indicam

Hi Terry,

I haven't checked the bearings for oil. It's brand new, so I figured it would have enough. I'm guessing sewing machine oil would probably be about the best viscosity, right (IE, very light)? Before I oil the bearings, though, I'll wait to see what Glidecam has to say about the issue.

I've not made any modifications to the Glidecam in any way, except to glue on the spirit levels this weekend. I haven't tightened the handle bolt assembly, for example.

If I move the rig rapidly forwards and backwards, it pendulums a bit, but nowhere near as much as side to side.

Now, where did I put those Aspirin?

Julian,

Our sled is similar in configuration to Glidcam's but with some important differences so we're familiar with it's basic operation.

Do this for me...Hold the sled by the post so that the handle hangs freely. Now move the sled back and forth and see it the handle moves very easily. Since it's a new sled I'm guessing it's fine but that doesn't explain your problems. FYI, we oil with a 3-in-1 viscosity type oil.

Try this out also...Static balance the sled forward with a 2-3 second drop-time and then pan the camera 180 degrees. Does the post stay vertical or does it swing out?

Are your weights on the bottom plate the same distance and equal in number (weight) from the post?

Tery
Indicam

Hi Terry,

Yes, the handle swings freely, I notice no sticking of any kind. There is some play in the handle, as I described earlier. Also, as previously described in an earlier message, the sled does not remain balanced when the handle is rotated 180-degrees (or camera panned).

As described in the first message in this thread, I have a total of 8 weights on the bottom plate, two sets of 4. They both started out at the extreme ends of the plate, but, to get the rig to balance again (after the camera came back heavier from the repair facility!), they've since been moved in towards the central post by about 1/4". I ended up fine-tuning the balance by moving the weights because the manufacturing tolorences I talked about above, meant I was "chasing" the balance and unable to get perfect static balance. However, in reading Charles Papert's posts about dynamic balance, he says to move the camera in the direction where's it's heaviest, and move the weights on the base plate in the opposite direction (IE. If it's front heavy, move it forward a little, then move the weights under the lens backwards to compensate). So, even though the weights are symmetrical in my case, they don't necessarily have to be!

Glidecam responds to my 4000 Pro problems
 

I got en email from Tom at Glidecam. He agrees that there may be a problem with my gimbal being out of spec, and has asked me to ship the 4000 Pro back to him. I'm going to use the current setup for a test shoot this weekend, so I'll send it to him on Monday. He said he'll test my unit and either trim it, or replace it as necessary. I don't care either way, I just want to be able to use it to its full potential. Anyway, Glidecam was very responsive (they got the email this morning, and replied immediately with a solution) so I'm happy so far. I'll update this thread with my findings when I get the unit back in a couple of weeks.

did you purchase the Glidecam brand new, or are they repairing it regardless of when it was purchased?

I bought it brand new, through one of the dealers listed on the Glidecam web site. my guess is they'll replace it with a new one, which hopefully they will fully test for linearity prior to sending it to me.