* GadgetBuilder.com *
Last Modified:
Click to Enlarge
A cutter grinder has been high on my tool list because most all my end mills are dull. I built a Mini-Tinker but couldn't figure out how to sharpen end mills with it, only touch them up. A cutter grinder is expensive so I was preparing to (and eventually did) build a Brooks-Stent type but some software work on a FORTH system for an HCS12 in need of interrupt handlers came my way making a modest price cutter grinder purchase possible - perhaps my youth wasn't as mis-spent as I thought - real time programming skills are still useful ;-)
I chose the "Universal Cutter Grinder" from Wholesale Tool which was very similar to the unit (since discontinued) from Harbor Freight; a friend bought the HF unit and the units share a manufacturing defect so they may come from the same factory - just painted different colors. WT ships by truck: more expensive than HF who ship by UPS but my machine arrived undamaged; repair parts for my friend's HF machine took 10 weeks to arrive. My machine arrived on May 23, 2006.
Chinese machine tools are a bit of an adventure and this machine is no exception. Simple inspection showed a few obvious problems: the bolts for the handles on the drawbars for the work heads protruded such that the drawbar base couldn't seat properly (easily fixed), the barrel around the "adjuster screw" on the lathe tool head was too large to fit into the hole (easily fixed), the adjustment for moving the arbor axially was rough, noisy, and hard to turn (moderately easy to improve), and the grinding wheel supplied is rated 4775RPM max (visible here) while the spindle on my machine turns 5500 (? called WT about this, their site says 6K spindle RPM, seems like a serious safety issue), the hook spanners shown in WT's picture on the web were not included (WT will supply shortly) and the indexing work head has a rough spot in its rotation but I can't get it apart without the missing spanners. Having purchased a Homier minilathe, most of this is not unexpected. Overall, it seems like a sturdy machine which needs some TLC and attention to detail to make it work to its potential, much as my minilathe required.
WT called on 2 June 06: spanners are on order, they are working on getting 1.25" wheel adapters, and the included wheel is marked wrong - it is rated 6600 RPM not 4775 as marked. I am unwilling to verify this by actually using the wheel so have ordered a CBN taper wheel which should be good to 10k RPM. In my discussion with WT on adapters I noted that 1.25" hole adapters to fit the taper on the shaft are needed, one for each wheel so the wheel doesn't require re-truing when swapping; hard to say whether they and the Chinese manufacturer really understand or will supply adapter bushings to adapt 3/4" to 1.25 instead (I could make these easily, the taper is where the difficulty lies). If they supply bushings I'll have to make the taper adapters which will be a considerable task - probably need to make a taper reamer to get it right, may be able to use the grinder to make this reamer. WT has been responsive through this confusion so I'm fairly happy with how things are going although the wheel situation is questionable.
The Wholesale Tool manual does not include a specification (e.g. spindle RPM) and the parts list has a number of errors, making reference to parts by name difficult. The HF manual on the web has a partial parts list but some parts are mis-labeled so it is not trustworthy either. The Deckel SO parts manual is helpful but the Chinese version differs in a number of areas. In summary, I have not found any solid documentation so far. Especially, I haven't found any information on how to use this machine to sharpen end mills... However the concepts should be the same as for other machines.
On 30 August the spanners arrived from WT but the 1.25" adapters which I had been awaiting were not included. I called WT and wasn't able to get a date for delivery of the 1.25" adapters. I asked to return the unit since I can't easily use it to sharpen end mills (my real goal) without these adapters; WT agreed to take the unit back so on 5 September it was returned (fortunately, I kept the crate). Wholesale Tool remained pleasant and helpful to deal with throughout, the problem was that the Chinese manufacturer did not follow through on their promises.
Notes on my very limited use of the Universal Cutter Grinder: I purchased a Norton straight cup wheel for a 3/4" spindle which was rated for this unit's RPM. I was unable to sharpen end mills with this wheel, in particular I could not grind the third angle (i.e. gash) although this would likely have been possible with a taper cup wheel. I found the angles possible for the head were more limited than I expected because the movement to the right is constrained by the bar support on that end. When set up to sharpen end mills it is difficult to see and evaluate the result as grinding proceeds. The stop for the traverse motion around the bar (used to stop grinding at the center of an end mill) is not sufficiently precise for my needs; the Deckel design is considerably more refined in this area. Also, I didn't see a simple way to sharpen slitting saws -- so this unit wasn't as "universal" as its name implied, at least in my inexperienced hands. Others find they can sharpen end mills with it so don't take my word for what this machine can do. However, I remain convinced the Stent type design is far more intuitive to use and jigs required for specific cutters are easier to make.
If you have a comment on my site or its contents, click here.
