Wilson/Sinclair Trimmer Micrometer Length Discrepancies

[RickKr]

I recently received a Wilson Trimmer with the Sinclair micrometer head. I started trying it out and have a curious situation. The micrometer seems to not "read" the correct case length, once trimmed, compared to the actual measured case length. The case is actually about 0.010" shorter than the micrometer reading.

I've checked the micrometer using precision gauge blocks, over its range (1.3"-3.0"). I placed these precision gauge blocks on the rails, supported so they are inline and placed a 0.010" brass "shim" (feeler gauge) between the cutter head and the gauge blocks to protect the cutting teeth. Adjusting for the additional shim thickness, the micrometer reads reasonably accurate over its range, about 0.001" off at 1.3" and 2.0", but is off by about 0.003" at 3.0". Not as good as I'd like, but something I could work with. The cutter head has been clamped against its bearing so I know the cutter is not moving/changing.

I have a previously trimmed case that measures 2.474". I set the micrometer for that case length. But when I put that case, in the right holder, on the trimmer, there is a 0.010" gap between the end of the case and the cutter head. I can put a 0.010" feeler gauge between the end of the micrometer head and the case head. I've checked the trimmed case mouth to confirm there are not cutter indents that might cause this sort of thing. In order to trim other cases, I have to move the micrometer head/stop in that amount in order to trim, so I know

I've very perplexed about this discrepancy. I've emailed Sinclair, but it is the weekend so no response expected for a few days. I realize this is something I could "learn to work with", but after paying the money for a supposedly better and more accurate trimmer/micrometer, I think I shouldn't have to do that. Plus, the Sinclair info, both online and in the instructions lead me to believe the case should come out the same as the micrometer reading, within a reasonable tolerance, but 0.010" discrepancy is way beyond what I call reasonable.

I'm curious is anyone else has seen anything like this or have any ideas what might be causing it.

Rick

PS: The third image, showing the case on the trimmer, shows the micrometer adjusted to the actual length of the case and the micrometer reading is 2.465", rather than the measured length of 2.474". The last photo shows the insertion of the feeler gauge with the micrometer reading 2.476".

 

[Gappmast]

I had the old style Wilson trimmer and purchased the micrometer attachment later. It did not read correctly when I first installed it and I had to make some adjustments. Now it is spot on within less than 1/2 thousands. Loosen the silver knob on the back of the thimble and adjust it like a regular micrometer.

 

[RickKr]

I had the old style Wilson trimmer and purchased the micrometer attachment later. It did not read correctly when I first installed it and I had to make some adjustments. Now it is spot on within less than 1/2 thousands. Loosen the silver knob on the back of the thimble and adjust it like a regular micrometer.

Yes, they are adjustable. I fully appreciate this fact and have actually adjusted mine. That is the point of the first photo in my OP showing the micrometer reading 2.010" with a 2.000" precision gauge block and a 0.010" brass feeler gauge between the mic head and cutter head.

My question is more about why it would not read/set accurately with a case when it does with these gauges.

Certainly, I took the Sinclair instructions literally when they say that the micrometer has been "zeroed" at the factory. I took that to mean the micrometer would be reading something close (within 0.001"?) on the mic as what was being measured. My observations and measurements are not bearing that out.

I'm sure some, and perhaps you, mean that the mic can be adjusted to read/reflect what the case measures when it is held on the trimmer. That definitely can be done, but there is no assurance that it would hold or be accurate for other cases/lengths. I can try this to find out. But, part of my question is why would I have to do it this way.

But even that - "...why would I have to do it this way..." is not my primary question. That primary question is "why is it happening"? And to extend that, if I understand why, is there anything I can do to rectify it so these readings do correspond.

 

[Fast14riot]

Have you put your calipers on the gauge blocks to verify?

 

[RickKr]

Have you put your calipers on the gauge blocks to verify?

Most certainly, yes. I should have shown at least one with the OP, but I thought it was already getting a bit pedantic. Don't very often have the calipers go out of wack, with being able to close them and set to zero, but it happens.

 

[RickKr]

It did work to adjust the micrometer thimble to match the actual case length, for the most part without reference to the gauge blocks, etc.. The version of Sinclair micrometer head that I have is a little funky to adjust as it is captured by a set screw and not a screw thread. Once the set screw is loosened, the thimble is loose and floats anywhere. So it was not a simple matter of just rotating the thimble a little, it also would slip in or out, so I had to carefully maintain its position in relation to the graduations on the thimble sleeve. A minor annoyance, really.

Even so, I was not that pleased with the Sinclair micrometer head. It was a bit stiff to rotate and I didn't care for the 50 thous. per revolution graduations. Too accustomed to the old standard machinist micrometers, I guess. I got a Mitutoyo 2" travel head that reads just like standard micrometers, with 25 thous. per revolution. I machined a bushing to mount it to the Wilson trimmer base, put in a set screw for clamping the spindle sleeve and a lock finger knob.

The spindle graduations are much easier for me to read (old brain pathways) and the thimble spins freely and travels much faster than the Sinclair. After setting it up, based on case length and not worrying about gauge blocks, it is dead on, over the range I'll be using. 22-250 to Wby 257.

Over-kill, for sure, but I like it.

Rick

 

[michaeljp65]

With all due respect Rick, you can't use a 1" or 3" gauge block to verify the callipers if your measuring in the hundredths or thousandths. You need a gauge block in your measuring range.

 

[AlNyhus]

The issue is likely the case holder to case fit. -Al

 

[RickKr]

The issue is likely the case holder to case fit. -Al

Al,

Could you please elaborate? I am not clear what you mean.

The case holder's job it to hold the case at the proper height and parallel with the centerline axis. Length of the case is determined by the distance between the caliper anvil and the cutter. It should still work if the case isn't exactly on centerline and I can see how the trimmed case mouth might be canted if the case were not held parallel.

I haven't check for either, but at this point, the issue is resolved with the micrometer mod.

Rick

 

[RickKr]

With all due respect Rick, you can't use a 1" or 3" gauge block to verify the callipers if your measuring in the hundredths or thousandths. You need a gauge block in your measuring range.

With all due respect in return, I do not agree, particularly with regard to measuring in the hundredths (±0.01"). If I were a parts inspector, perhaps, trying to determine compliance at the thousandths level (±0.001"). That is not the situation. Exact measurements is not issue. The initial issue was discrepancy and inconsistency on the 0.01" level. Achieving reasonable agreement of the result of the trimming process with a known standard (to the extent a micrometer meets this) was the issue. As someone commented, the Sinclair micrometer can be repositioned. It could, but I found the process for repositioning it klunky. I also didn't care for the "feel" of the Sinclair mic. So I went overboard with the Mitutoyo mic head. I am satisfied with the result, which is within acceptable length and consistency.

To your point, a gauge block measurement was made with the calipers within 0.01" of the case being measured (shown) at 1.900". Are you saying that, for the requirements of case trimming, I should have used gauge blocks stacked to exactly 1.900"? I could do that, but I sure don't see the need.

Rick

 

[ridgeway]

I just cut, measure, cut measure and once set, run em. I could care less what the micrometer depth stop says. As long as all the cases are trimmed and repeats.

 

[Sniper338]

Measure the case with calipers, then use it to take whatever you need off, remeasure. Once you find where it needs to be set you can lock it down. No need trying to dial it in for the first.. trial and error, then lock it down

 

[jackson1]

Man, I must be completely out of touch with the world. Using reference marks ( micrometer head on a case trimmer) as a measuring devise, is just plain wrong. I'm jaded I know, spent my life in a machine shop. If I ever attempted to turn a precision diameter, by touching the tool to the workpiece and dialing in the numbers, I would been the laughing stock of the shop. Seen a ton of boo boos in my life and made some myself, but this has to be right up there. I know many of us here did not have the benefit of learning on some else's dime, so I can't be to hard on your assumption. Whenever possible use the proper tool for the job, it works way better. Have mic heads on my Wilson trimmer and my Wilson seating dies and love them for what they are. Always sneak up up on your desired dimension. Another small rant; your dial caliper is not a man portable CMM. My bad.

 

[epc308]

You think you had problems, my plain Jane Wilson came with a piece of coarse all thread for the stop. Try sneaking up with one of those. I found a Starrett micrometer head on an unused, outdated measuring device in the tool room, so it wandered home with me after one night shift. Like others, I made a bushing and mounted it on the Wilson. It isn't set to measure exact length(s), but it's dead on repeatable to numbers I have recorded. PS- even after proving itself again and again, I still use the sneak up method.

 

[Willie]

You think you had problems, my plain Jane Wilson came with a piece of coarse all thread for the stop. Try sneaking up with one of those. I found a Starrett micrometer head on an unused, outdated measuring device in the tool room, so it wandered home with me after one night shift. Like others, I made a bushing and mounted it on the Wilson. It isn't set to measure exact length(s), but it's dead on repeatable to numbers I have recorded. PS- even after proving itself again and again, I still use the sneak up method.

Yep! I have a list on a bulletin board for all settings to trim to. My stainless cutter has bit the dust, but I had a carbide cutter just waiting for it's turn.
If I'd known how great it is, it wouldn't have stayed in a drawer for 4 years.

Only con is I have to redo my list of trim lengths.

 

[michaeljp65]

With all due respect in return, I do not agree, particularly with regard to measuring in the hundredths (±0.01"). If I were a parts inspector, perhaps, trying to determine compliance at the thousandths level (±0.001"). That is not the situation. Exact measurements is not issue. The initial issue was discrepancy and inconsistency on the 0.01" level. Achieving reasonable agreement of the result of the trimming process with a known standard (to the extent a micrometer meets this) was the issue. As someone commented, the Sinclair micrometer can be repositioned. It could, but I found the process for repositioning it klunky. I also didn't care for the "feel" of the Sinclair mic. So I went overboard with the Mitutoyo mic head. I am satisfied with the result, which is within acceptable length and consistency.

To your point, a gauge block measurement was made with the calipers within 0.01" of the case being measured (shown) at 1.900". Are you saying that, for the requirements of case trimming, I should have used gauge blocks stacked to exactly 1.900"? I could do that, but I sure don't see the need.

Rick

Sorry Rick, your correct in what your saying. My fingers were typing before my brain was thinking.

 

[BenPerfected]

Rick, have you talked to Sinclair? I would be surprised if they wouldn’t be able to help you.
Ben

 

[JFrank]

I just cut, measure, cut measure and once set, run em. I could care less what the micrometer depth stop says. As long as all the cases are trimmed and repeats.

My standard non microwave.. do dad cutter works perfectly using a feeler gage behind the cutter head to set the desired length. And bam !! All good

 

[ScottVA]

I have the older version and in all honesty, I only use the depth mic on the tool to adjust the amount to remove. Ive never set it to a case length and I have never looked at what it's reading. I make my measurements with the caliper, adjust the cut with the depth mic, and start trimming. They are very repeatable