Col2310
9th September 2010, 09:01 PM
See old thread
I ordered an ER32 Collet Chuck to suit my Hercus from Chronos UK at the end of May and after numerous emails, pressing for a delivery date, received the item on 6th. September. Most of the replies from Chronos related to the failure of their supplier (Soba India) to meet the delivery schedules but one reply concerned the rejection of one batch for quality reasons. I should have taken the hint and cancelled the order.
The fitting on the thread was good and tight without any significant movement 'fore or aft' and the fit on the register was good .
I was very pleased at this stage and placed a test bar in a 20mm collet and clocked it 0.07mm TIR...not too good.
I removed the collet and nut and ran the clock on the internal taper with the same result. So removed the chuck and ran the clock on the Hercus spindle register which gave a zero result, so all errors were in the collet chuck.
I emailed Chronos, stating my disappointment with the accuracy, as I had hoped to the maximum TIR would be around 0.01mm.
I had a reply today apologising for the poor accuracy, refunding the purchase price and postage and suggesting that I bin the Collet Chuck. They added that they could not replace the product with an item that would give the accuracy I requested.
Their quick response and immediate refund has to be commended.
I think it is possible to rectify the runout by re-machining the internal taper which should not adversely affect the collet clamping if I removed only a minimum amount.
Any comments on this? or should I scrap it?
I have an air driven Dremel type grinder which I could adapt and mount on thecompound. The grinder has a 6mm collet, supposedly runs at 25000rpm.
If I used this, what type and size of grinding wheel do I need and where do I find one?
I ordered an ER32 Collet Chuck to suit my Hercus from Chronos UK at the end of May and after numerous emails, pressing for a delivery date, received the item on 6th. September. Most of the replies from Chronos related to the failure of their supplier (Soba India) to meet the delivery schedules but one reply concerned the rejection of one batch for quality reasons. I should have taken the hint and cancelled the order.
The fitting on the thread was good and tight without any significant movement 'fore or aft' and the fit on the register was good .
I was very pleased at this stage and placed a test bar in a 20mm collet and clocked it 0.07mm TIR...not too good.
I removed the collet and nut and ran the clock on the internal taper with the same result. So removed the chuck and ran the clock on the Hercus spindle register which gave a zero result, so all errors were in the collet chuck.
I emailed Chronos, stating my disappointment with the accuracy, as I had hoped to the maximum TIR would be around 0.01mm.
I had a reply today apologising for the poor accuracy, refunding the purchase price and postage and suggesting that I bin the Collet Chuck. They added that they could not replace the product with an item that would give the accuracy I requested.
Their quick response and immediate refund has to be commended.
I think it is possible to rectify the runout by re-machining the internal taper which should not adversely affect the collet clamping if I removed only a minimum amount.
Any comments on this? or should I scrap it?
I have an air driven Dremel type grinder which I could adapt and mount on thecompound. The grinder has a 6mm collet, supposedly runs at 25000rpm.
If I used this, what type and size of grinding wheel do I need and where do I find one?