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Y.T.

Selecting disc sander for small scale modeling

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Posted (edited)

It took me a while to make my mind on what disc sander I really need. I build small scale wood ship models. I live in condo (Toronto). First, my sander must be very precise. Second it must have a variable speed motor so I can do precision work on different type of materials without burning them. Third it must be compact as I live in condo. Forth vacuum connector is very beneficial.  I had to exclude all sanders with disc + belt. These have no precision and no variable speed motor. Byrnes disc sander is a Cadillac of sanders for modellers but has no variable speed motor. This video below helped me a lot for making my decision. I arrived to same conclusion as Paul Budzik did in this video. I need Proxxon that one of a smaller size - 5" (125 mm) disc diameter. I searched for a better price for it everywhere. Best I could get in for in Canada was CAD325 on Amazon.CA. Suddenly the seller went out of stock and item became unavailable. Now it sells for about CAD520 with no particular explanation for price increase. I found a sander from different supplier and of similar but slightly different design.  It has all features of Proxxon 5" sander or they at least claim that they have. It costs only CAD$100 and of course made in China. All features listed are a copy of Proxxon sander I wanted including a power of the motor. Looks is quite different (no one can say it is a PIRATED COPY 🤮 ). I was contemplating for a while and bought it on Amazon.CA. Amazon has great return policies. I will check it out and tell you how good it was. If no good I would just return it back to Amazon.

 

 

 

 

 

 

71aSpom1X-L._SL1500_.jpg

Edited by Y.T.

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Hi Y.T.

That's identical to the one I bought from a Lidl supermarket in Basel,except mine is green with another name. Cost me the princely sum of 34 Swiss francs. I'm very happy with it's performance at all speeds plus it's pretty quiet. If you are sanding very small pieces I recommend making a small table to temporarily clip on it's table as the gap from the disc is about 1/4" at 90°. I'm sure you wont be disappointed with it. Have fun making dust :D

 

Dave :dancetl6:

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Hi. I just got this sander I spoke about. All looks not bad. There is some small runout on the disc. I do not have a dial to actually measure it but please look at the video. Does it look as bad runout? Does Proxxon 5" disc sander have better runout?

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I'm not seeing it but that doesn't mean it's not there.   How bad is the runout?  The other question is "can you live with it being less than perfect?".   Try sanding something and see if it's something you can live with.

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Run out is very small. I think some runout would be present on any disc sander. I do not want to return this unit and purchase a Proxxon 5" sander for CAD$400 just to find out that it has same runout or worse. I think I could try living with it for CAD$100 (about US$75).

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I've one that both a disk and belt sander.  There is runout on the disk but slow feed and it works.  I only use if for rough sanding and to get down the last bit, I had sand or use files.

 

Fire that thing up and run some tests on scrap wood and see if it will work for you.

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On 8/6/2019 at 1:11 PM, davyboy said:

Hi Y.T.

That's identical to the one I bought from a Lidl supermarket in Basel,except mine is green with another name. Cost me the princely sum of 34 Swiss francs. I'm very happy with it's performance at all speeds plus it's pretty quiet. If you are sanding very small pieces I recommend making a small table to temporarily clip on it's table as the gap from the disc is about 1/4" at 90°. I'm sure you wont be disappointed with it. Have fun making dust :D

 

Dave :dancetl6:

Hi Dave, I took this sander apart out of curiosity. I easily minimized the gap by unscrewing a set screw which fixes the disc on the shaft and shifting disc away from the motor and tightening a set screw back. Now I have no gap. Surprisingly this also reduced the noise somehow. Cheers!

 

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11 hours ago, Y.T. said:

There is some small runout on the disc. I do not have a dial to actually measure it but ...

There is one simple thing that can tell you a lot about the sander: check that the groove for the mitre slide (on the bed) is true to the disc. Make something like a piece of scrap wood to fit snugly into the groove and glue a piece of wood or stiff card to it so it just touches the disc face. Slide it back and forth and see if a gap appears. It should be consistent.

It may sound like heresy but as long as there is a small amount of consistent runout, you can get good results if your sliding mitre is correctly aligned. I expect not everyone will agree.

Regards,

Bruce

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Actually I was able to measure the runout with digital caliper. It is 4 thou at deepest spot. I think this should be satisfactory. See picture. Please let me know if it’s good. 

725F585D-73ED-4E7E-A286-0BE4C0FD1244.jpeg

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28 minutes ago, Y.T. said:

Please let me know if it’s good. 

I think the best test would be to check the relationship between the mitre slot and the face.  From the photo it looks like you are measuring from the edge of the table. 

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Y.T.

I think 0.004 of an inch is as good as one could expect. One could have that much variance in the grit of the paper. Besides, we aren't building parts for the Space Shuttle.

RussR 

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Posted (edited)

I started sanding edges of 1 x 2 mm boxwood strips at 12 degrees angle. Works perfectly. Tilting table feature helps a lot. I work with microns here as strips are window frames and should fit into existing cavities perfectly.  

BC6CB717-373A-47B7-B606-ED3C018D377A.jpeg

Edited by Y.T.

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8 hours ago, bruce d said:

There is one simple thing that can tell you a lot about the sander: check that the groove for the mitre slide (on the bed) is true to the disc. Make something like a piece of scrap wood to fit snugly into the groove and glue a piece of wood or stiff card to it so it just touches the disc face. Slide it back and forth and see if a gap appears. It should be consistent.

It may sound like heresy but as long as there is a small amount of consistent runout, you can get good results if your sliding mitre is correctly aligned. I expect not everyone will agree.

Regards,

Bruce

I"m confused. Is it really "run-out" that you're talking about? I believe run-out refers to the face of the disk being perfectly aligned perpendicular to its shaft. If it isn't, the disk will still sand a straight line as long as the piece is held against the miter gauge and run across the face of the disk. It may be just the edge of the disk that does the sanding in that case, but it will be straight as long as the piece runs true against the disk. A much greater problem is with a shaft and disk which are not perfectly aligned to the miter slot. The easiest way to check that quickly is to run the work piece directly into the disk while against the miter gauge set at a right angle and sand an edge on it, then turn the sander off and turn the piece over and slide the piece against the fixed miter gauge and the just-sanded edge up against the disk face. If the miter gauge slot and the disk face a perfectly parallel, the edge of the turned over piece should exactly align with the disk face. If it's off at an angle, the slot and the disk face are out of alignment. (If you wonder why your mitered corners aren't coming together to form perfect right angles, slot and face alignment is the cause.)  You won't have this problem with a Byrnes Model Machines sander.  "You get what you pay for" and accuracy costs more. I always wonder how it is people think that less accurate tools "are sufficient for modeling purposes" when the smaller the scale, the more critical the accuracy becomes to the quality of the finished work.

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Hello Bob,

I assume the part of my comment you are pondering is 'a small amount of consistent runout'. I don't know if runout is the correct phrase to describe variation in a disc sander, it has not been something I ever discussed in detail with a disc-sander-qualified engineer. I take runout to be a variation in true running of something circular. That fits with the way the term was used in the thread.

The test you describe is different from the test I was describing because my interest was strictly with the relationship between the slot and the disc face: I did not want to complicate matters by involving the mitre sled which may or may not have been a good fit in the slot and may or may not have been capable of locking into 90 degrees without flexing (as you say, you get what you pay for).

So I suggested the test I have carried out on every disc sander I have used as an adult by checking if the slot and disc face are parallel. Found a couple that were out by a mile, a couple that were spot-on bullseyes and a few that were out a bit.

One of the issues the test will highlight is if the disc is not flat. This is different from 'not running true' which can come from the disc face being flat but not at a perfect 90 degrees to the spindle. If the disc has a face that is slightly concave or convex, it may still be possible to get good results if there is a good portion of the disc that is flat and the operator works strictly in that area. Far from ideal but that is life iif you ain't got a Byrnes.

Hope this helps,

Bruce

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2 hours ago, Bob Cleek said:

...I believe run-out refers to the face of the disk being perfectly aligned perpendicular to its shaft....

I also believe same. See test I did with caliper above. What is this runout on Byrnes 5" disc sander?

 

image.thumb.png.8f88b1272a8572ce11bb153d8cefd13f.png

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Sorry, I'm at the office (and should be working! :D ) so I don't have my Byrnes sander handy. I can put a dial indicator on it over the weekend and see. (Now you've got me wondering!) I have never perceived any runout (disk wobble) or misalingment with the miter gage slot whatsoever. I'll post back when I get a chance to measure it. 

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Posted (edited)

Here is a disc sander I made up from mini "lathe" I have. Disc is 60mm aluminum lid from some medicine jar. I successfully use it for small strips mitering for a while already. Looks funny but it really works. Conclusion is yes, we have to have good tools to do the job. It is often with cheap tools one can do good job. Sometimes very expensive tools do not help. Byrnes disc sander?

Edited by Y.T.

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9 minutes ago, Bob Cleek said:

Sorry, I'm at the office (and should be working! :D ) so I don't have my Byrnes sander handy. I can put a dial indicator on it over the weekend and see. (Now you've got me wondering!) I have never perceived any runout (disk wobble) or misalingment with the miter gage slot whatsoever. I'll post back when I get a chance to measure it. 

Hi Bob, thanks for reply. Working so late on Friday night? Do not overwork yourself. Yes. Please measure and let me know whenever you feel comfortable. Have good weekend!

 

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Well,I have always understood run-out is a radial measurement used to check out if shafts are turning straight and true in their bearings and not eccentrically. Did enough run-out checks on helicopter drive shafts etc in my working days. Fore and aft wobble on a sander disc has IMO nought to do with run-out. Just saying.

 

Dave :dancetl6:

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Posted (edited)
35 minutes ago, davyboy said:

Well,I have always understood run-out is a radial measurement used to check out if shafts are turning straight and true in their bearings and not eccentrically. Did enough run-out checks on helicopter drive shafts etc in my working days. Fore and aft wobble on a sander disc has IMO nought to do with run-out. Just saying.

 

Dave :dancetl6:

You are correct. Here "run out" is used to describe anything turning. Think of the face of a disk sander as the end face of a five inch diameter shaft. 

Edited by Bob Cleek

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51 minutes ago, Bob Cleek said:

You are correct. Here "run out" is used to describe anything turning. Think of the face of a disk sander as the end face of a five inch diameter shaft. 

Hi Bob,then the term "run out" here is being used incorrectly.

 

I don't know if Y.T. did a check on the opposite face of the disc immediately after but any difference there (keeping the disc stationary) from his .004" measurement

would indicate to me that :-

 

(A) the motor is not aligned up horizontally square on it's mounting bracket/s.

(B) the disc itself is slightly warped or badly machined.

 

Anyway we're talking about a cheapo Chinese product here not a Byrnes sander ;):D

 

Dave :dancetl6:

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Posted (edited)

Actually I started to work on my new "cheapo Chinese product" and I am very happy with it. I can do on it exactly what I need. From what I learned it is pretty much an affordable substitute for Proxxon 5" disc sander. I do not know why I would need Byrnes disc sander especially if it is 5 times more expensive.

Disc wobble relative to table is 0.004" I consider this wobble being negligible. I doubt any other sander has better disc wobble characteristic than this including Byrnes. Besides I can change disc speed in range 1150-3600 RPM which Byrnes cannot do. Motor has plenty of torque even at slowest speed. I connected my Hoover vacuum cleaner to it and have zero dust when I work.

Edited by Y.T.

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Here look how I use new tool. I had to make stern side window separator posts for my 1:90 Victory. They must be exactly as measured on 22.5 degree angle. I made a contraption of piece of wood found in dollar store which connects to miter tool. It helps delivering a very small piece of work to a sanding disc.

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Posted (edited)
On 8/9/2019 at 1:49 PM, Y.T. said:

I also believe same. See test I did with caliper above. What is this runout on Byrnes 5" disc sander?

 

image.thumb.png.8f88b1272a8572ce11bb153d8cefd13f.png

I got around to putting my dial test indicator on my Byrnes sander. I got +/- .002" at the outside edge of the disk, which is a solid plate of about 1/2" aluminum. I tested the outer side of the disk which is parallel to the shaft to get true runout. The miter gauge slot is perfectly aligned with the face of the disk based on a visual check of the miter gauge edge against the disk face, but there's some play in there due to the +/- .002" runout on the shaft. Close enough for government work, I'd say.

 

I also checked the miter gauge accuracy against my Starrett protractor, which is very accurate and found the guage was right on the money, but I didn't find that surprising, given that it's CNC machined. The thing I really like about the Byrnes miter gauges (the same on both the saw and sander) is that they have pins that set the frequently used angles, 90, 45 degrees, etc., perfectly and with 100% repeatable accuracy. There's no fiddling and eyeballing (and, if you want to be sure, setting up with a separate accurate triangle) to make sure a pointer on the index is right on the money. Any angle setting is possible with a set screw, as well, of course, but for the commonly used angles you know you're on the money first time, every time.

Edited by Bob Cleek

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