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Please note that THECRAFTSMANGALLERY have now replaced this Caliper with an updated version, a review of which is to follow. Now since this type of caliper is available from other sources (but not the mounting kit) this review will remain in place for information in the short term.

The Craftsman Gallery Digital Caliper Kit

Click any picture to enlarge

Well here we are again, yet another rainy day. Seems to me the only difference here in the deep South West between summer and winter is the temperature of the rain! Its time for another review. Before I start, I must be open and honest and say that initially I was a little reluctant to test this kit. The reason is that the WoodRat is not designed as a metal working milling machine: I believe sufficient accuracy is achievable without resorting to digital measurement and working to within one thou' is not needed. Let's not lose sight of the fact that we are working with wood here.

 O.K. with that off my chest, Lewis Stepp has produced this kit in response to demand and so with curiosity and an open mind I made a start.

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 Included in the kit is a  nicely boxed Chinese made but quality hardened stainless steel digital caliper, (vernier in the UK). The box includes instructions and a spare battery. In the bag are the usual Craftsman Gallery excellent instruction leaflet, a white nylon mounting plate with two allen screws and, a pleasant surprise, to complete the kit, a 4mm tap.

This kit is designed for measuring North/South travel of the router on the plate and since the caliper can be zeroed at any position and works in either millimetres or decimal inches is very convenient. Please note that this kit is designed to be mounted on the alloy rails and is not suitable if you have the earlier white plastic ones. The instructions,  apart from explaining the mounting procedure also give details of how to use it in creating sliding dovetails.

 

 Lewis has very cleverly utilised the fact that the jaws of the caliper are tapered and so can be placed into the fence bar hole and set to give a slop free fit. It should be suitable for most routers with East/West bar holes although I can't of course confirm this.

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  The next step is to place  the nylon mounting plate on the rail and to mark the position of the bolt holes onto the rail. Taking time and care over this will pay dividends later.  Ensure that the router is pushed right back against the rear stop, then place the end of the caliper jaw  into the fence bar hole. With a little jiggling around a combination of depth and angle will be found that removes all slop. Place the nylon pad under the fully extended vernier and carefully position it as shown in the photo. Arrange that the small rail fixing screw is not covered whilst not intruding over the jaw measuring area.

I used a pop punch to carefully mark the hole positions. Remove the rail and find a 1/8 inch drill to drill the holes. I used a drill press to ensure the holes were vertical.

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 I then tapped the holes with the 4mm tap included in the kit. For some reason I can never get a perfectly square thread when manually turning the tap and so I use the drill press with some wax lubricant in the hole and turn the chuck by hand. Result: good, clean vertical threads.

The instructions call for the caliper to be fixed to the pad with hot melt glue. I didn't have any and so elected to use two small strips of double sided fixing tape. That stuff is strong so I only wanted to use small pieces. It did occur to me that Velcro tape could also be used for easy release.

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It was now a simple matter to place the end jaw into the bar hole, adjust to remove slop and fix it down onto the pad.

With the router pushed back the depth bar of the caliper fully protrudes out 6 inches beyond the plate and threatens to stab you in the stomach (especially mine!!). For this reason the Craftsman Gallery recommend cutting it off with a Dremel and abrasive disc. I am sorry. I tried to pluck up the courage, I really did but this act of vandalism on a such a useful precision tool just appalled me and I couldn't bring myself to do it.

 

 If you got the original positioning of the nylon plate right, when unbolted from the rail the digital caliper can still be used whilst still attached to the  base as shown here.

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 In Conclusion

This is another kit from the Craftsman Gallery that is well presented  and comprehensive as shown by the inclusion of a 4mm tap. At $38 U.S., I recommend it as it is worth the price for the digital caliper alone which is so useful that I could not now be without it. It  requires some commitment to cut off the  depth bar, however the fixing was simple and straight forward but does require care to avoid any slop or play.  The concept of bringing the bit up to just touch the work and then pushing a button to display zero and moving on a set amount clearly displayed before you is wonderful. The display is at right angles to your normal viewing position but is still clear enough to read without contorting your neck. I tested this with a DeWalt 625 but the actual mounting method means that it should be fine with many different makes of router providing that the fence holes are orientated the correct way.

I personally had one difficulty. I found sliding the router n/s to creep up to a predefined measurement frustrating. For example to move from say zero to 0.5" I would keep ending up a few thousands either side of  the mark. i.e. 0.494 or 0.504 for example. Ah hah my opening remarks confirmed! In his description of how make use of the calliper when cutting sliding dovetails Lewis suggest tapping the router base with a small hammer forwards or backwards to sneak up to the exact display position. I am not sure that I care for this approach. I understand the reasoning, (I have tried it and it works) but think that a small purpose made wooden mallet or leather faced object would be more appropriate and leave less opportunity for minor damage or chipping.

I mulled over this for some time and ---Wow!! Suddenly there was light! I opened the digital caliper to a reading of 10 thou' inches (0.27mm), held it up to the light and noted that in woodwork terms that is one very small space indeed so a setting of say 3 thou' either side of the desired position could be considered to be extremely accurate. In my opinion in real life, a gap this small  is still too tight and doesn't allow for a decent glue-line or ease of fitting.

The notion that to purchase this kit for working on the WoodRat to within 0.001 of an inch, to me, is not a valid one. To purchase one to make positioning accurate, simple and viewable on a clear numerical display most certainly is. I am very content to work to a few thou' inches on the loose side of a joint and this kit is just perfect for this.

As an aside, I noticed on this caliper that the display did not auto shut off after a short time. There is no mention about it in the instructions so to preserve battery life, remember to switch off when not required.

I have read I think on one of the earlier 'Rat forums before it died that some people have concerns that over time vibration from the router will kill the display. I don't know but the caliper does not need to be mounted all the time. I have yet to see a report that this has actually happened.

I am relieved to say that my initial reluctance to use this kit was ill founded but still maintain that super accuracy is not needed. I will very likely use it a lot.

For more information on The Craftsman Gallery products visit their web site www.chipsfly.com

The Craftsman Gallery Pdf


Addendum

I suspect that a few new owners may be reluctant to purchase this kit because they have have to make holes in their shiny new rails. So as an experiment I made up this slot mounting acrylic holder. Acrylic machines very well on the WoodRat with ordinary router bits and glues very well with cyanoacrylate (super) glue.

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I used 1/4" scrap to make it. I routed the under side of the base to leave a shallow raised ridge that is an accurate fit in the rail slot. Just like the standard WoodRat alloy sliding bracket or the Craftsman Gallery precision stop. The digital caliper is perfect for measuring this!!  I cut out some small pieces for the sides. A round rasp soon had the piece that fits around the ribbed battery holder profiled to a snug fit. A short pan head phillips 5mm screw sits in a recess in the base as a fixing. I used a brad point wood drill to make the hole central on the ridge of the base.

Again lay down the digital caliper so that there is no play in the fence bar slot and when satisfied with the position super glue the sides on as shown in the photos. The sides must be carefully set so that there can be no sideways or forward movement. I actually had to make a second one before I was entirely happy. The observant may notice a little mistake on the front edge but it doesn't matter, (remember to lock the depth stop on your router!)

I used a scraper to tidy up the edges. It works very well and is a simple matter to just locate the jaw into the hole and drop into the holder. There you are, definitely no excuse not to purchase the Craftsman Gallery Digital Caliper now!!

"I suggested a digital caliper for sliding dovetails for several reasons:

            1.  Using a digital caliper you can easily determine the tenon cut (subtract neck of female cut from width of tenon board and divide by 2).

            2.  You can zero the bit then zero the caliper.

            3.  But most important, you can sneak up on the cut.  Since the calculation does not allow for glue, the calculated cut is likely to be too tight.  You can tap the base of the router to add a slight amount to the cut and know how much more you are adding.  Otherwise, you might tap too hard and not be able to reposition.

The caliper is giving you information.  The fact that it reads in thousands is incidental to the fact that you now have the information you need.

   Lewis Stepp, The Craftsman Gallery


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