Upgrade the O-RING of Goot / Soldapullt desoldering tool - Page 1
Forum section: electronics / general

author: kamcm
author_rank: Regular Contributor
timestamp: January 13, 2019, 02:55:19 am
content: I found that the Goot desoldering suckers sucks in performance due to the original o-ring mismatch with the o-ring holder.The original O-ring core dimension: 2.4MM , with a outer dimension of 18MMThere's tons of gap.I decided to upgrade it with a more fit-size o-ring.At first, I try out a 3.2MM O-ring (The green one)The 3.2MM O-ring is much better then the original one but still having a little gap.I decided to go for a bigger size o-ring, 4MM core dimension with a outer dimension of 18MMThe 4MM O-ring is the perfect match of this sucker.

author: Ian.M
author_rank: Super Contributor
timestamp: January 13, 2019, 04:25:19 am
content: Actually the O ring needs to be free floating in its groove to work properly. Excessive O ring thickness will force the O ring to deform to fit the bore, increasing friction and drastically reducing the suction, by slowing the plunger down. If the O ring is a snug fit to the cylinder bore, but free floating in the groove, it will seat against the tip side of the groove as the plunger moves, and the vacuum it pulls will act to keep it in good contact with the groove side and cylinder wall, without excessive friction. If your 4mm O ring can still be freely spun in the grove by light fingertip contact, its probably OK, otherwise you should go down a size on thickness.Its unfortunate that your sucker's plunger has no provision for a wiper to reduce the amount of solder dust that reaches the O ring and upper bore, as solder dust in the bore and on the O ring and groove side is one of the leading causes of poor suction. Frequent cleaning of the bore and O ring groove area of the plunger assembly with a dry old toothbrush helps considerably.For suckers that use a compression spring in the chamber, its possible to make a wiper out of paper disks, trapped between the spring and the plunger. For details see reply #16 and photo at #43 inhttps://www.eevblog.com/forum/repair/de-soldering-advice-loosing-my-mind/The best you can easily do with your plunger is to have a loose fitting O ring in the groove nearest to the tip to try to keep the dust away from the O ring providing the main seal.

author: amyk
author_rank: Super Contributor
timestamp: January 13, 2019, 05:30:06 am
content: In other words, your o-rings are lined up in that picture in the order: Goot, better, best.

author: kamcm
author_rank: Regular Contributor
timestamp: January 13, 2019, 07:20:04 am
content: Quote from: Ian.M on January 13, 2019, 04:25:19 amThe o-ring I replaced have the outer dimension 18MM which is same as the original one.The only different is the core dimension.In fact, the unmatched O ring thickness will lead to the o-ring unable to hold its shape at the time movement in action. It also force the O ring to deform within the o-ring holder and it drastically reducing the suction.I also have HAKKO SPPON, Engineer SS-02 desoldering tool and I can tell none of them using a unmatched o-ring.

author: stj
author_rank: Super Contributor
timestamp: January 13, 2019, 07:48:41 pm
content: that was clearly designed for 2 o-rings.fit a second one.

author: KL27x
author_rank: Super Contributor
timestamp: January 15, 2019, 12:07:56 am
content: ^It's not designed for two o-rings. Ian.M is correct. The groove should ideally leave at least a little space on the sides of the ring to reduce friction. It is a tight seal to the body, but there's some lateral room for the O-ring to "grow" out, laterally.Without this room, the O-ring has to be just the right fit AND the ID of the housing has to be very precise (and it's not, because it's molded plastic), else you will get some losses due to friction and/or vacuum loss due to gap. Or both.That's not to say that the OP didn't improve his sucker. Sometimes the O ring just doesn't seal well due to parts tolerance in production and poor quality control. If the replacement O-ring is a tight squeeze in the groove, it might work as good as it gets, if your housing is very uniform. But in a mass produced product, that little gap adds some room for error.With a tight groove, an O-ring can exert a lot of pressure. It's elastic, but it's not much more compressible than water. In making o-ring stoppers for jars/bottles, I have discovered this firsthand. The O -ring changes shape only to a small degree. It's not silly putty that will easily squeeze into tight corners or completely change shape. At least not without a lot of force (which in this case means a lot of friction).

author: stj
author_rank: Super Contributor
timestamp: January 15, 2019, 04:21:27 am
content: the green rings btw are FKM, they are a lot harder than the black ones.

author: floobydust
author_rank: Super Contributor
timestamp: January 15, 2019, 05:49:00 am
content: What are you using to lube the cylinder? Some greases are not compatible with o-ring materials, maybe it's all puffed up. I usedLubriplate 100white tube, calcium base worked good.

author: eKretz
author_rank: Frequent Contributor
timestamp: January 15, 2019, 01:43:07 pm
content: The ring doesn't have to be tight to seal. You also don't want a very hard ring at low pressures. O-rings are designed to deform to seal gaps. You want low friction so the piston can move fast to create suction instantly. The ring will extrude itself with differential pressure to fill and seal the gap. The makers of these devices know what they're doing, they're not idiots.

author: Ian.M
author_rank: Super Contributor
timestamp: January 15, 2019, 03:21:55 pm
content: A further thought: To provide an effective low friction wiper, try a couple of turns of thick woollen yarn in the groove nearer the tip, *NOT* pulled tight, with the ends stitched through its self to stop it unwinding.The trouble with lubrication is: grease or oil heavily loaded with fine solder dross is *NOT* a good lubricant, and if the bore is made of plastic, it may even act as an abrasive grinding paste. Additionally, buildup of solder dross 'spooge' on the side of the O ring goove will prevent it sealing effectively. It also makes cleaning the O ring and its groove much harder. Therefore I would recommend the sparing use of a dry film lubricant on the bore and O ring or a single drop of light oil*wiped round the bore then after cycling the mechanism a few times, wipe off any excess at the limits of the plunger travel, and on the O ring.* The oil must be compatible with the cylinder, plunger and O ring. A silicone oil is typically compatible with most non-silicone plastics and elastomers, and we used to use silicone fuser oil for photocopiers as we had a near limitless supply. In addition to damage to the O ring and bore if plastic, using the wrong oil is a possible hazard if the plunger is plastic as eventually the plunger may crack freeing the shaft of compression spring suckers to fly out and possibly hit you in the face next time its used, or releasing the spring of tension spring suckers, which may hit the knob on the end of the shaft hard enough to break that loose liberating the spring and knob as a projectile. IMHO a quality solder sucker should be of all metal construction with the exception of its tip, any O rings, other seals and wipers required and the knob on the end of the shaft.

author: kamcm
author_rank: Regular Contributor
timestamp: January 15, 2019, 03:25:56 pm
content: Quote from: eKretz on January 15, 2019, 01:43:07 pmThat 's not true.With the original O-ring. It having at least 1.5MM gaps in both Y axis and X axis.At the time the piston in action, the O-ring unable to hold its position, it will twist out of shape and lost most of suction instantly.Green line represent the gap between the original o-ring and o-ring holder.Look at the shape and the edge of the original o-ring. It's already twist out of shape. That's what happened when o-ring free floating within the o-ring holder.IMO, The o-ring should not be free floating within the o-ring holder / socket.

author: Southerner
author_rank: Regular Contributor
timestamp: January 15, 2019, 03:44:17 pm
content: I would also like to know what you are using for lube. I saw comments of what type not to use. Or are you saying not to use any lube at all?

author: kamcm
author_rank: Regular Contributor
timestamp: January 15, 2019, 03:50:23 pm
content: Quote from: Southerner on January 15, 2019, 03:44:17 pmI use this one, it's plastic safe

author: eKretz
author_rank: Frequent Contributor
timestamp: January 15, 2019, 05:21:49 pm
content: The o-ring is a wear item. Did you expect it to last forever? Spend the $5 and get a whole bag of them. Hardened solder, flux and all the other garbage that comes from desoldering is what is doing the damage to your o-ring. It has nothing to do with the fit in the groove.

author: kamcm
author_rank: Regular Contributor
timestamp: January 16, 2019, 12:38:14 am
content: Quote from: eKretz on January 15, 2019, 05:21:49 pmI don't mean to offend you but you are completely wrong.When the fit-size o-ring installed within the holder.When the o-ring free floating within the holder. This green gap will leak air and it lost most of suction instantly.Is it really hard to understand it?

author: fsr
author_rank: Regular Contributor
timestamp: January 16, 2019, 01:22:33 am
content: I buyed one of that goot desoldering tools, and it broke fairly quick. It seems like the plastic was too thin for the force of the spring. Very dissapointed with it, as the price was higher than a generic chinese tool, but the quality was not.

author: kamcm
author_rank: Regular Contributor
timestamp: January 16, 2019, 02:10:22 am
content: You should tryout hakko or ss-02.PerformanceHAKKO SPPON 20G★★★★★★★★ 8/10Engineer SS-02★★★★★★★★ 8/10Chinese tool ( unknown brand)★★★★★ 5/10Goot GS-104(Original O-ring)★★ 2/10Goot GS-104(3.2MM o-ring)★★★★★★ 6/10Goot GS-104 (4MM o-ring)★★★★★★★★ 8/10I have the experience of using different desolder suckers.I would say the goot desolder sucker is a piece of junk with the original o-ring.However, the goot performance line up with hakko after I change it to 4mm o-ringIt make a huge different and that is why I share it on this forum.Proskit PK-366N★★★★★★ 6/10

author: amyk
author_rank: Super Contributor
timestamp: January 16, 2019, 02:33:30 am
content: In other words, you could say it was not very... Goot.With all you spent on those, maybe it would be better to buy an automatic desoldering iron.

author: eKretz
author_rank: Frequent Contributor
timestamp: January 16, 2019, 02:25:08 pm
content: Ok man. It's funny that everyone else who has used a Goot didn't really have any problems. Myself included. And I own a few others as well - an Engineer like yours and an Ersa as well. If they are maintained I find that they all work about the same.

author: TimeBandit
author_rank: Regular Contributor
timestamp: December 02, 2019, 02:58:21 pm
content: I want to order a pack of O rings from McMaster Carr for my soldapults, but the choice of material is bewildering: Fluoroelastomer (hard or soft), Fluorosilicone. Silcone, etc. I'm thinking just the cheapest high temp silicone ones will be fine. Thoughts?https://www.mcmaster.com/o-rings/=54b015fe60a049f6b9710afdadb33e03k3ok3y7m

author: Ian.M
author_rank: Super Contributor
timestamp: December 02, 2019, 04:22:05 pm
content: You don't actually *need* a high temperature O ring - by the time the solder dross hits the plunger at the end of the stroke, its significantly cooled and the chances of a big enough still molten droplet coming in intimate contact with the O ring so it can transfer enough heat to do damage are vanishingly small, or zero if you've managed to retrofit some sort of wiper to protect the O ring.Select hardness rating 'Soft' as its a low pressure application, and you only get two choices left: High-Temperature Soft Silicone O-Rings @ $5.54 per 10, and Chemical-Resistant Soft Viton® Fluoroelastomer O-Rings @ $9.45 per 10.Remove the high temperature restriction and you get one more:Oil-Resistant Soft Buna-N O-Rings @ $9.50 per 75Any of those three should do the job - Viton would be the best for lubricant compatibility, and is probably more wear resistant than Silicone, which is incompatible with silicone oils and greases (they swell and soften silicone rubber badly). However Buna has superior abrasion resistance to the others and has the lowest cost per O ring which may be important if you are maintaining a *LOT* of suckers on a tight budget.

author: KL27x
author_rank: Super Contributor
timestamp: December 02, 2019, 06:50:18 pm
content: Quote from: kamcm on January 15, 2019, 03:25:56 pmBut the friction against the side of the tube will keep the O-ring to one side. In this pic, pushed flat against the bottom.I have opened my own soldersuckers. They are all made like this and they work great. OTOH, I have seen examples of DP-100 exactly same as mine, purchased from Mouser, like mine. And it didn't work at all. No seal. The O ring was too small relative to the body. This needed some tweaking to the O ring to get it to work, at all. So yes, your sucker wasn't working. But no, it wasn't because of this feature.The seal doesn't have to be perfect for the sucker to work. It has to be adequate. It's better to allow a small bit of leak vs increasing friction too much. Hence, the gap in this groove on either side of the O-ring is intentional.Yes, there is a failure rate using this intentional gap. If you make 1000 of them, maybe 20-30 won't work, due to tolerances. But if you tried to make them the way you imagine, 50% of them wouldn't work without hand tuning. And even the ones that work perfectly, the o-ring will, on average, suffer greater wear and lower longevity before the device stops working. This because the tube is not perfect. Molded plastic has some warpage that has to be considered in the tolerances.

author: TimeBandit
author_rank: Regular Contributor
timestamp: December 02, 2019, 07:02:06 pm
content: Quote from: Ian.M on December 02, 2019, 04:22:05 pmThanks Ian. This is the perspective I was hoping for. I do use a light coating of silicone O ring grease when installing these, so I'll likely go with either the Viton or Buna.

author: nukie
author_rank: Frequent Contributor
timestamp: December 16, 2019, 03:03:47 am
content: If you block the white tip with your finger and press the fire button. Does the plunger return quickly or do you feel any leakage. My Goot gave my finger a good suck, plunger did not return, which means the O ring is working as it should. There is a constant vacuum. The plunger return as soon as I release my fingers.