Fluke 289 plastic threads - Page 1
Forum section: electronics / testgear

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 21, 2015, 03:16:52 pm
content: I was wondering why my Fluke 289 doesn't have metal thread inserts inside the plastic components where screws are inserted for the most part.I've already managed to ruin the threads on one of them due to constant opening and closing of the meter so why did they not use metal thread on all of the screw housings?Seems like a stupid design oversight to me from a benchmark DMM and of Fluke quality

author: BravoV
author_rank: Super Contributor
timestamp: February 21, 2015, 03:30:50 pm
content: Agree, at their top class 28X series DMM, they definitely can do better than that ...Close up photo on the 28X thread insert, after I saw this, when every times I tighten the screws, so worry that I over doing it that will crack this fragile plastic.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 21, 2015, 04:22:21 pm
content: Quote from: BravoV on February 21, 2015, 03:30:50 pmThat's exactly what I am talking about. It's absolute nonsense for a 600 $ DMM!

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 21, 2015, 04:34:05 pm
content: I find that a bit ofsiliconegrease on the threads (and a subsequent reduction in tightening torquedue to the lower friction) helps the threads to last longer. Be sure to rotate the screw backwards until you feel the thread catch in the same spot - some people find that helps avoid cross threading.I'll add that metal inserts are only better when properly designed. I've seen metal inserts twist out, break out, etc. because the wrong insert was used, or there wasn't enough plastic to support it. I havean AmprobeA Triplet meter with metal inserts that are all broken - I wish they had gone with self tapping screws.EDIT: D'oh. It's a Triplet, not an Amprobe. I shouldn't have violated my "Fluke only" rule.ANOTHER EDIT: I guess some words weren't prominent enough, so I added bold font and underlining.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 21, 2015, 04:38:12 pm
content: Quote from: Excavatoree on February 21, 2015, 04:34:05 pmI'll give your suggestion of using silicone grease a try but still that doesn't eliminate the fact that if slightly over-tightened, the plastic threads might get drilled out of break.Fluke's implementation of metal thread inserts should be first class since they are one of the top quality meters in the world. I might understand if they broke on your Amprobe meter since they are owned by Fluke as a "budget line" measuring tools company but Fluke cannot afford such a mistake.

author: SeanB
author_rank: Super Contributor
timestamp: February 21, 2015, 08:30:10 pm
content: Simplest solution would be to but some brass inserts and fit them in, or just drill out the hole and tap it for a recoil insert of appropriate size with a matching screw. You put the insert in with some loctite red ( and then wash out the hole so the screw will come out as well afterwards) or superglue, then you have a metal insert that wears well.

author: dadler
author_rank: Unknown
timestamp: February 21, 2015, 08:33:09 pm
content: I must be doing something wrong-why are you takings the meter apart regularly?The fuses are available without removing any screws.

author: oldway
author_rank: Super Contributor
timestamp: February 21, 2015, 08:50:13 pm
content: Yes, I agree, Fluke is going the wrong way with the new models !Working with power electronics, I only use Fluke multimeters.I have an old 73 (buy in 1993), a 23 series II and a 87 V...they are all very great multimeters. (87 V is the best, in my opinion !)But I have also a 87 IV (same as 187) and I am not satisfied at all with it.1) Too little autonomy.2) Input jack receptacle too weak. Broken and hard to find (and very expensive)3) battery clips corroded and also very hard to find (and very expensive too)For this late multimeter, thumbs down...

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 21, 2015, 10:20:35 pm
content: Just for the record, it is a Triplet, not an Amprobe. It's not built nearly as well as their old analog meters used to be.

author: LabSpokane
author_rank: Super Contributor
timestamp: February 22, 2015, 02:18:11 am
content: Don't put grease in the holes. Oils can attack the plastic over long enough a time and will cause the bosses to disintegrate. I'm guessing that it is a polycarbonate or PC blend, which might not like extended contact with a petroleum product.Don't use superglue! Just don't! Use epoxy. Super glue will attack certain engineering resins and cause the bosses to disintegrate.Properly installed inserts do not come out without a shitload of force. They are either molded in or sonic welded in. The design to do this isn't rocket science. All one has to do is read the data sheets.Fluke doesn't install inserts purely for cost reasons. There's a way (a couple actually) to sonic weld them in quickly but most companies don't like investing the manufacturing development costs to do so. It makes a better product, but it's a pain in the ass and is definitely a source of scrap.The Danaher Business System thanks you for your support.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 22, 2015, 03:08:40 am
content: Quote from: LabSpokane on February 22, 2015, 02:18:11 amI did not suggest to use petroleum grease; the silicone grease I recommended is inert, and does not attack the plastic that Fluke uses. I've tested this, and would not have recommended it if I didn't know there would be no adverse effects. I do agree that petroleum grease may cause problems.The 27 requires silicone grease for the seals that contact the screws, and this has been used for several years with no problems. Silicone grease is also specified for use on the gaskets that seal the older 27 type and the newer 28 meters. These gaskets come in contact with the plastic with no detrimental effects.

author: Robomeds
author_rank: Frequent Contributor
timestamp: February 22, 2015, 03:34:00 am
content: I've disassembled many devices using screws into plastic. You must be careful when putting the screws back in. I would also second the question, why take the meter apart in the first place? Don't get me wrong, I like taking things apart (I posted a number of meter tear downs). But I'm also careful when doing so because I have learned over the years to have a soft touch with screws into plastic.

author: Ericho
author_rank: Regular Contributor
timestamp: February 22, 2015, 03:44:14 am
content: Do not use any lubricant at all.You increase the axial forces on the already fragile plastic tread for the same amount of screw driver torque.It increases the risk of damaging the treaded connection.It also increases the risk of damage due to cheamical reactions between plastic and grease.My 289 has a battery compartment, so I'm ok with the rest of the screw in plastic connections. if these screws need to be undone frequently then there is something wrong with the rest of the device, not with the screws.looking at those pictures, longer screws and tapping the tread deeper (with the correct tools) may be an option as a permanet repair.Or epoxy or similar as a teporary repair while a new part is on order.Kind regards,Eric

author: retiredcaps
author_rank: Super Contributor
timestamp: February 22, 2015, 03:50:33 am
content: If the OP is the original owner of the 289 and bought it from an authorized Fluke dealer, be aware that any alteration to the meter may/will give grounds for Fluke to deny you any warranty. So don't go modifying the screw holes to add metal threaded inserts.

author: BravoV
author_rank: Super Contributor
timestamp: February 22, 2015, 04:19:30 am
content: Quote from: Ericho on February 22, 2015, 03:44:14 amAgree, as the the plastic stand is quite long, and also the original thread is not that deep, and there is still left quite long enough, non threaded wall at the deeper part of the tube.Here another angle of the plastic stand :

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 22, 2015, 02:31:20 pm
content: Quote from: Ericho on February 22, 2015, 03:44:14 amI did add to reduce the applied torque. By applying less torque to drive the screws, the bosses aren't stressed as much. It's worked very well for me. I've been re-assembling Fluke meters like that for 10 years and haven't had a problem.The question was asked "Why disassemble it?" Well, the 280 series meters had the capacitor that had to be replaced. Those who could get them change under warranty did so, but the meters still had to be disassembled. Crusty, used meters can be cleaned and/or repaired, if necessary. Many models require that the case screws be removed to change the battery. (Older 87s, 10 series, 70 series, 70 tapered series, possibly some others)Since I started working on modern, plastic items, I've learned not to tighten them as much. I've found, at least for the plastics I've worked with, that initially one can apply too much torque, and everything seems fine, but later, the threads strip easier.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 22, 2015, 04:21:49 pm
content: Quote from: retiredcaps on February 22, 2015, 03:50:33 amI don't give a rats ass about warranty so that's not a concern for me.

author: necessaryevil
author_rank: Regular Contributor
timestamp: February 23, 2015, 07:48:58 am
content: QuoteYou really don't care about the lifetime warranty on a $600 dollar multimeter?

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 23, 2015, 08:27:45 am
content: Quote from: necessaryevil on February 23, 2015, 07:48:58 amNot at all. I've already modified the multimeter to I can charge the batteries without removing them or run it with a DC power supply.I would rather have the multimeter work the way I want it to than to have lifetime warranty.

author: BravoV
author_rank: Super Contributor
timestamp: February 23, 2015, 09:27:41 am
content: Quote from: drummerdimitri on February 23, 2015, 08:27:45 amI'm interested, as I got my two 287s at great price from grey market (so no warranty), share & post the mod job in a new thread please.About recharging and external DC, I assume those are fully and "decently" isolated right ?